System and method for estimating cardiac pressure using parameters derived from impedance signals detected by an implantable medical device

Abstract

Techniques are provided for estimating left atrial pressure (LAP) or other cardiac pressure parameters based on various parameters derived from impedance signals. In particular, effective LAP is estimated based on one or more of: electrical conductance values, cardiogenic pulse amplitudes, circadian rhythm pulse amplitudes, or signal morphology fractionation values, each derived from the impedance signals detected by the implantable device. Predetermined conversion factors stored within the device are used to convert the various parameters derived from the electrical impedance signal into LAP values or other appropriate cardiac pressure values. The conversion factors may be, for example, slope and baseline values derived during an initial calibration procedure performed by an external system, such as an external programmer. In some examples, the slope and baseline values may be periodically re-calibrated by the implantable device itself.