A monitoring and/or stimulation device to receive a signal from a lead sensor positioned in the heart of patient. The monitoring and/or stimulation device processes the blood pressure data received from the sensor to determine an augmentation pressure for each heart beat. The augmentation pressure may be tracked over time or compared to a template to determine the circadian state of the patient. The augmentation pressure may be tracked or analyzed over a longer time period to detect other heart conditions such as hypertension.