A method and a device to deliver heat and mechanical agitation in a liquid with ultrasound. The method and device may be used for thermal treatment of tissue within a living body, the device comprises a housing extending from a distal end to a proximal end, the housing including a first opening exposing an inner chamber of the device to the fluid, the housing being sized and shaped for insertion to a target location within the body and a piezoelectric element fixed within the housing and generating pulses of ultrasound energy directed substantially along a longitudinal axis of the housing in combination with first and second deflecting elements, the first deflecting element being mounted within the housing on a distal side of the piezoelectric element, the second deflecting element being mounted within the housing on a proximal side of the piezoelectric element, the first and second deflecting elements deflecting a portion of ultrasound energy from the piezoelectric element away from the axis of the housing so that the deflected ultrasound energy exits the housing via the first opening.
