An implantable device and method for monitoring changes in the risk of arrhythmia induced by medications. The method involves processing the input signals to determine first parameters describing relative phase difference and temporal difference between the signals, and applying these first parameters to process the input signals to generate intermediate signals. The bus slave can accept multiple write addresses such that there can be copending write transactions to the same bus slave. The adaptive control system may additionally control magnetic fields within the ion source. The sustainer amplifier has an output, from which the drive signal transfers sufficient energy to the string driver transducer to sustain the vibrations of the strings.