An implantable monitoring device for monitoring a patient's heart rate variability over time. The device includes a cardiac electrogram amplifier, a sensing electrode coupled to an input of the amplifier, timing circuitry, processing circutry and a memory. The timing circuitry defines successive monitoring...http://www.google.ca/patents/US6508771?utm_source=gb-gplus-sharePatent US6508771 - Method and apparatus for monitoring heart rate
