Compound barb medical device and method

A method of forming a compound barb on a medical device, comprising the steps of:

• applying ultrasonic energy to a cutting element of a barb cutting apparatus;
• moving a medical device against the cutting element at an angle relative to a longitudinal axis of the medical device to form a compound barb on at least a portion of the medical device including:
• forming a first cut in the medical device, the first cut having a first ratio of cut depth to diameter of the medical device;
• and
• forming a second cut in the medical device, the second cut having a second ratio of cut depth to diameter of the medical device;
• and
• varying a signal amplitude of the ultrasonic energy applied to the cutting element after forming the first cut to alter the second ratio of cut depth to diameter from the first ratio of cut depth to diameter.