METHOD AND APPARATUS FOR ACCURATELY DETERMINING HEART RATE VARIABILITY AND SYMPATHETIC RESERVE

摘要

An implantable monitoring device is disclosed 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 circuitry and a memory. The timing circuitry defines successive shorter time periods during each monitoring period. The processing circuitry relies upon electrogram activity that occurs during rest periods that extend as long as T1, all of which is stored into memory. Active periods are not considered as part of the heart rate variability calculation. The processing circuitry calculates median intervals between depolarizations of the patient's heart sensed by the amplifier during the shorter time periods and calculates a standard deviation of the median intervals during T2, a longer monitoring period.

主权项

1. A device for monitoring a patient's heart rate variability comprising:
a sensing electrode to detect a cardiac depolarization; a sense amplifier coupled to the sensing electrode to produce a signal indicative of a detected cardiac depolarization; an activity sensor to generate a signal indicative of activity; processing means for measuring intervals between successive cardiac depolarizations; a timing means for defining successive shorter time periods during a longer monitoring period; processing means for using the signal for determining whether a patient is active; processing means for using data from the signal for determining rest periods that extend as long as the shorter time period; processing means for determining cardiac intervals occurring during each rest period; storing means for storing the measured cardiac intervals; processing means for calculating a central tendency metric of the measured cardiac intervals during each rest period; and in response to calculating the central tendency metric, processing means for determining a coefficient of variation of the cardiac intervals during the rest periods within the longer monitoring period to generate the heart rate variability.