One general aspect includes a system for ablation including a catheter including a sheath defining a sheath lumen and a distal end, and an elongate electrode assembly axially moveable within the sheath lumen. The electrode assembly includes a shaft defining a central channel and a distal central channel opening. The electrode assembly also includes an expandable electrode array including two or more electrode elements positioned at the distal portion of the electrode assembly, where the electrode array is moveable between a retracted position contained within the sheath lumen and an expanded position protruding from the sheath.