Ablation apparatus is provided. The apparatus includes an ablation electrode shaped to define a cavity thereof, and comprising a metallic distal face that is shaped to define a plurality of apertures. A fluid-delivery channel is configured to deliver fluid to the apertures. At least one ultrasound transducer is disposed within the cavity of the ablation electrode, the transducer being configured to transmit an ultrasound wave through the apertures. Other embodiments are also described.
