An embodiment uses an accelerometer to sense heart sounds, and determines heart rate information using the sensed heart sounds. An embodiment uses an accelerometer to sense respiratory activity. An embodiment delivers a programmed neural stimulation therapy with a programmed duty cycle, where the programmed duty cycle includes a stimulation ON portion followed by a stimulation OFF portion. An electrode electrically connected to the implanted neural stimulation device is used to remotely detect cardiac activity. The remotely detected cardiac activity is used to detect heart rate information during the stimulation ON portion and to detect heart rate information during the stimulation OFF portion. The detected heart rate information and/or the detected respiration information are used to control a neural stimulation therapy performed by the neural stimulator device and/or are used to provide diagnostic information for the patient's condition.