Abstract: A system includes a first coil, a signal source and a first control module. The first control module regulates coupling between the signal source and the first coil. The system also includes an implantable device having a second coil coupled to a therapeutic transducer comprising an ultrasonic transducer. When the first coil is aligned with the second coil, the signal source is able to supply electrical power to the implantable device to enable the therapeutic transducer to operate. The control module is able to activate the therapeutic transducer under the control of a physician.

Abstract: A parameter indicative of the condition of a cardiac valve is determined by monitoring blood flow and/or velocity in a vessel that is coupled to the cardiac valve or in a chamber adjacent to an artificial cardiac valve. One or more ultrasonic transducers are provided either in a wall or a cuff disposed about a cardiac vessel to monitor the parameter in regard to a natural or artificial cardiac valve, or in a support sewing ring of an artificial cardiac valve. A conformal array transducer or a tilted element is used to monitor fluid flow or velocity based on the effect of the blood on ultrasonic waves produced by the transducers. The conformal array transducer comprises a plurality of elements that are excited with an input signal provided by an implantable electronics circuit, producing ultrasonic waves. Transit time or Doppler measurements are made using an appropriate number of these transducers to determine either blood volumetric flow or velocity.

Abstract: A parameter indicative of the status of fluid flow is remotely monitored in a vessel, a natural graft, or a synthetic graft. One or more transducers are provided either in a wall of a synthetic graft or adjacent to a vessel or natural graft to monitor the parameter. A conformal array transducer or a tilted element is used to monitor fluid flow or velocity through the graft or vessel based on the effect of the fluid on ultrasonic waves produced by the transducers. The conformal array transducer comprises a plurality of elements that curve around the graft or vessel and are excited with an input signal provided by an implantable electronics circuit, producing ultrasonic waves that propagate into the fluid flowing within the graft or vessel. Transit time or Doppler measurements are made using an appropriate number of these transducer to determine either fluid flow or velocity.

Abstract: A stent or graft stent energized from an external power source is provided with one or more sensors to sense a parameter, producing a signal that is transmitted outside a vessel in which the stent is implanted. At least a portion of a body of the stent or an insulated electrical conductor comprises a plurality of turns that serve as an RF antenna. An expandable mesh or helical coils that form the stent body may serve as the antenna or it may comprise a separate insulated conductor. The RF antenna receives energy electromagnetically coupled to the antenna from an external (or implanted) coil and conveys a data signal corresponding to the parameter sensed by the sensor(s) on the stent or stent graft to a monitor disposed outside the patient's body. In one form of the invention, a plurality of conformal array transducers are used to produce and sense ultrasonic waves that are affected by a fluid flowing through a lumen of the stent. This transducer determines fluid flow or fluid velocity.