Electrode catheter with incremental advancement

1. Apparatus for use with a blood vessel of a subject, the apparatus comprising:

a longitudinal member, having a distal portion that is transluminally advanceable into the blood vessel;

a plurality of electrodes disposed on the distal portion of the longitudinal member, such that a first electrode of the plurality of electrodes is disposed distally along the longitudinal member from a second electrode of the plurality of electrodes, wherein the distal portion of the longitudinal member has an operational shape in which it is curved to define a helix, the plurality of electrodes is distributed in a helical arrangement along the distal portion of the longitudinal member; and

a controller, comprising:

circuitry electrically connected to the electrodes via the longitudinal member, and

an actuator, mechanically connected to the longitudinal member, and configured to move the longitudinal member in discrete incremental movements distally and rotationally such that for each incremental movement, (a) before the incremental movement the first electrode is disposed in a starting position, (b) during each incremental movement the actuator moves second electrode toward the starting position of the first electrode, and (c) at the end of each incremental movement the second electrode is stationary at a location that is both longitudinally and laterally the same as the starting position of the first electrode;

wherein the circuitry is configured to drive the first electrode to apply ablative current, and to drive the second electrode to apply excitatory current.

2. The apparatus according to claim 1 , wherein:

the plurality of electrodes comprises a third electrode and a fourth electrode,

the third electrode is disposed distally along the longitudinal member from the fourth electrode, and

the actuator is configured to move the longitudinal member in incremental movements such that for each incremental movement, (a) before the incremental movement the third electrode is disposed in a starting position, (b) during each incremental movement the actuator moves fourth electrode toward the starting position of the third electrode, and (c) at the end of each incremental movement the fourth electrode is stationary at the starting position of the third electrode.

3. The apparatus according to claim 1 , wherein:

the plurality of electrodes comprises a third electrode and a fourth electrode,

the third electrode is disposed distally along the longitudinal member from the fourth electrode, and

the actuator is configured to move the longitudinal member in incremental movements such that for each incremental movement, (a) before the incremental movement the third electrode is disposed in a starting position, (b) during each incremental movement the actuator moves fourth electrode toward the starting position of the third electrode, and (c) at the end of each incremental movement the fourth electrode is stationary at the starting position of the third electrode,

wherein the circuitry is configured to, after each incremental movement, drive the first and third electrodes to apply ablative current, and to drive the second and fourth electrodes to apply excitatory current.

4. The apparatus according to claim 1 , wherein the actuator comprises a servomotor.

5. The apparatus according to claim 1 , wherein the circuitry is configured to drive the first electrode to apply ablative current, and to drive the second electrode to apply excitatory current after each incremental movement.

6. The apparatus according to claim 1 , wherein the circuitry is configured to configure the ablative current to have a frequency of 450-550 kHz.

7. The apparatus according to claim 1 , wherein the circuitry is configured to configure the excitatory current to have a frequency of 20-500 Hz.

8. The apparatus according to claim 1 , wherein the circuitry is configured to drive the first electrode to apply the ablative current independently from driving the excitatory current.

9. A method for using the apparatus of claim 1 , comprising:

advancing into a blood vessel of a subject the distal portion of the longitudinal member having the plurality of electrodes disposed thereon, such that the first electrode of the plurality of electrodes is disposed at the starting position, the first electrode being disposed, along the distal portion, distally to the second electrode of the plurality of electrodes;

using the controller to drive the first electrode to apply an ablative current;

using the controller to drive the second electrode to apply an excitatory current; and

subsequently, moving the longitudinal member distally and rotating at least the distal portion of the longitudinal member such that the second electrode moves toward the starting position of the first electrode, and stops at the starting position of the first electrode.

10. The method according to claim 9 , further comprising, subsequently to the step of moving the longitudinal member:

using the controller to drive the first electrode to apply an ablative current to tissue distal to the starting position of the first electrode; and

using the controller to drive the second electrode to apply an excitatory current to tissue at the starting position of the first electrode.