An RF ablation system includes an electrode element of elongate form and a cathode pad. A control unit includes a processing unit, a power unit and, optionally, a temperature sensor and/or an impedance sensor. The control unit in one embodiment carries out RF ablation in at least two phases, the first phase at a higher energy level and a second phase, after at least partial retraction of the anode element, at a second lower phase in order to close any remaining lumen within a blood clot formed within the vessel during the first phase. Other embodiments provide for sensing retraction of the anode terminal and effecting RF ablation during and/or after the retraction process in order to create a more effective occlusion barrier.
