Apparatus for use with a blood vessel (10) of a subject includes (a) a longitudinal member (92) that has a proximal portion and a distal portion, and includes an electrode (94, 124) disposed at the distal portion, the distal portion being transluminally advanceable to the blood vessel; and (b) a control unit (100), in electrical communication with the electrode, and comprising circuitry (102). The circuitry is configured to: (a) during a dual- signal period, drive the electrode to apply a dual electric signal that has (i) an excitation component that has a frequency of 20 - 500 Hz, and (ii) an ablation component that has a frequency of 5 kHz - 1 GHz; and (b) during an ablation-signal period that is separate from the dual-signal period, drive the electrode to apply an ablation electric signal that has the ablation component but not the excitation component. Other embodiments are also described.