A catheter includes a wave guide for transmitting ultrasonic energy from a transducer, and which is also rotated to facilitate enhanced disruption of the concerned obstruction in a transverse direction. Embodiments of waveguide include distal anchors that help focus the energy transmitted to a treatment site, and may also include a deployable filter that may open distal of the obstruction to capture any dislodged debris. Selectively inflatable balloons may cordon off a treatment site, and the wave guide may comprise a tube that may serve the dual purposes of inflating the balloon(s), as well as to transmit ultrasonic energy to an obstruction. A portion of an ultrasonic catheter may include plural curved portions to space an exposed portion of the wave guide away from the catheter body to enhance the vibratory action provided.