@gloaming
It may vary from facility to facility, but the procedure, as explained to me by my EP, begins with a CT scan of your heart /left atrial appendage, to determine firstly whether you are a candidate for a Watchman Device (left atria; appendages come in lots of different sizes and shapes and not all can accept the Watchman) and if you are a candidate, what Watchman Device is the right one for you (it's not a one size fits all gadget). Then your EP orders the specific Watchman Device that you need and it is shipped to the hospital prior to installation.