1. A method of guiding the placement or observing the operation of an invasive medical device comprising: operating an invasive medical device from an invasive medical device system to perform an activity within a body; operating an ultrasonic diagnostic imaging system to guide or observe the invasive medical device by means of a real time three dimensional ultrasonic image; producing information with the invasive medical device system having coordinate information relating to the activity; and merging information from the invasive medical device system into the real time three dimensional ultrasonic image at a location in the ultrasonic image data which is determined from the coordinate information.