Abstract: An apparatus includes a generator including a control module that is operably coupled to a power module. The power module is configured to produce an electronic signal to be received by an ultrasonic energy delivery assembly. The ultrasonic energy delivery assembly is characterized by a natural frequency, and the electronic signal is characterized by a frequency. The control module is configured to send a control signal to the power module to randomly vary the frequency of the electronic signal within a range defined at least in part by the natural frequency.

Abstract: An apparatus includes a transmission member having a proximal end portion and a distal end portion. The transmission member is configured to be inserted into a bodily lumen, and is configured to transfer ultrasonic energy from the proximal end portion to the distal end portion. The transmission member defines a lumen along a longitudinal center line of the transmission member. The distal end portion of the transmission member includes a concave engagement surface and a distal end surface. The distal end surface defines a plane that intersects the longitudinal center line of the transmission member at an angle of between about 75 degrees and about 105 degrees. The engagement surface is configured to engage a target tissue within the bodily lumen to limit movement of the target tissue along the longitudinal center line. The engagement surface defines an opening in fluid communication with the lumen.