Implantable devices for evaluating body-associated fluid transport structures and methods for using the same are provided. In some instances, the implantable devices include an elongated structure with at least one hermetically sealed integrated circuit sensor stably associated therewith and a transmitter. The devices find use in a variety of different applications, including monitoring the function of various types of body-associated fluid transport structures, such as arteriovenous fistulae, vascular grafts, catheters, cerebrospinal fluid shunts, and implantable central venous access devices.