An electrode for ablation therapy includes a flexible conductive element for conducting electrical energy and a flexible conductive polymer member in electrically conductive contact with the conductive element. A catheter shaft may be coupled to the conductive element and/or the flexible conductive polymer member. The flexible conductive element may be formed as a helical coil, a mesh coating or wrap, or any other suitable form, and may surround (wholly or partially) a flexible electrically insulative, and optionally thermally conductive, member. A heat sink may be thermally coupled to at least one of the flexible conductive polymer member and the flexible electrically insulative member. The flexible electrically insulative member may include a passageway for coolant fluid to cool the electrode during ablation. The passageway may include at least one efflux hole to permit coolant fluid to flow from the passageway, or may define a closed loop.
