Pressure is measured on both sides of an occluding member for determining when pressure forces on the occluding member may cause migration of the occluding member. An alarm indicates when the pressure force on the balloon exceed a predetermined threshold. In another aspect of the invention, a pressure...http://www.google.com.au/patents/US20010001812?utm_source=gb-gplus-sharePatent US20010001812 - Methods and apparatus for anchoring an occluding member
