Apparatus for treating obstructive blood flow disorders, is provided, including (1) an external device, configured for placement outside of a body of a subject and to sense a factor of the subject, and to generate a signal in response to the sensed factor, and (2) an implant, which comprises a wireless receiver for receiving the signal, and an effector element, the implant configured and positioned to alter a blood flow of the subject in response to the signal.
