Implantable Doppler system for self-monitoring vascular grafts

Most artificial vascular grafts fail within two years. To extend artificial graft life, an implantable Doppler system has been developed that can monitor the graft flow on a daily basis and communicate with a physician if the flow suggests impending failure. A special form of a diffraction-grating transducer (DGT), suitable for embedding in the wall of an artificial graft, has been successfully designed, fabricated, and tested. A paper design of an implant unit for use with this transducer shows such a unit can perform the daily monitoring and communication function for 10 years using a conventional pacemaker battery.