Apparatus and methods are provided, including an electrode that is placed in contact with an artery of a subject. A control unit drives the electrode to perform a function with respect to the artery, the function selected from the group consisting of: driving a current into the artery, and sensing an electrical parameter of the artery. A transmitter is placed in a vein of the subject that is in a vicinity of the artery, the transmitter being wiredly connected to the control unit. The control unit is configured to drive the electrode by wirelessly transmitting a signal via the transmitter. Other embodiments are also described.