An interventional medical device for use with a motion-sensitive ultrasonic imaging system comprising a flexible elongated member for insertion into soft tissue, a two-axis, flexing mechanism coupled to the flexible elongated member and a mechanism for controlled electrical excitation of the flexible elongated member. Each of the axial flexing mechanisms, when acted upon by electrical excitation, forcibly bends the elongated member along a section of it length causing its tip to move in the plane of the applied bending force. As a direct result of direct energy coupling by bending rather than vibration, the relative phases of the two axes can be controlled to accomplish specific movement of the tip of the flexible elongated member.