Patent ID: 7503895

Claim:
An ultrasonic medical device for tissue ablation comprising: an elongated probe having a proximal end, a distal end and at least two regions of differing cross sectional dimension, wherein a length of the elongated probe is configured to oscillate in a direction transverse to a longitudinal axis of the elongated probe to emit transverse ultrasonic energy along the length of the elongated probe so that a plurality of transverse nodes and transverse anti-nodes are formed along the length of the elongated probe; and a sheath assembly at least partially surrounding the elongated probe, the sheath assembly comprising at least one sheath defining a fenestration between a proximal and distal end of the at least one sheath, the at least one sheath being configured to substantially dampen ultrasonic energy such that ultrasonic energy delivered by the elongated probe is focused toward a region adjacent the fenestration.