A minimally invasive, implantable heart sound and ECG monitor and
associated method for deriving blood pressure from heart sound data. The
device is equipped with an acoustical sensor for detecting first and
second heart sounds which are sampled and stored during sensing windows
following R-wave and T-wave detections, respectively. ECG and heart sound
data are stored in a continuous, looping memory, and segments of data are
stored in long-term memory upon an automatic or manual data storage
triggering event. Estimated blood pressure is calculated based on custom
spectral analysis and processing of the first and second heart sounds. A
calibration method includes measuring a patient's blood pressure using a
standard clinical method and performing regression analysis on multiple
spectral variables to identify a set of best fit weighted equations for
predicting blood pressure. Concurrent ECG and estimated blood pressure may
be displayed for review by a physician.
