A hemodialysis and vascular access system which includes a catheter having an arteriovenous fistula utilizing an indwelling silastic venous end and an arterial end which is adapted to be anastomosed to an artery is described. In some embodiments, a message is received at a server. The circuitry of the present invention provides control of signal amplitude, frequency and phase to better than 1 ppm by making use of signal generation circuitry described pursuant to the present invention.