US 7,623,913 B2 · Implantable medical devices using heuristic filtering in cardiac event detection

Abstract

Methods for performing cardiac signal analysis in an implanted medical device, and devices configured to perform illustrative methods of cardiac signal analysis. A cardiac signal is captured by an implanted device using implanted electrodes and, during at least certain conditions, the cardiac signal undergoes heuristic filtering. In some embodiments, heuristic filtering is achieved by modifying a signal or value that is used as an indicator of received signal amplitude. In an illustrative example, the heuristic filtering includes periodically incrementing or decrementing the signal or value toward a desired quiescent point, where the heuristic filter period is significantly longer than the sampling period for the signal itself. In another illustrative example, the heuristic filter frequency can be adjusted dynamically to keep the signal average near the desired quiescent point.

Claims12

Dependent claims

A method of cardiac signal analysis comprising:

capturing a cardiac signal using implanted electrodes;
conditioning and amplifying the signal;
performing analog-to-digital conversion on the signal;
and
applying a heuristic filter to the captured cardiac signal by repeatedly performing the following at a predetermined interval:
a) calculating an actual quiescent point of the analog-to-digital converted signal;
and
b) adjusting the analog-to-digital conversion of the signal to modify the actual quiescent point toward a desired quiescent point;
and
adjusting the predetermined interval by calculating a quiescent distance between the actual quiescent point and the desired quiescent point;
and:
x) reducing the predetermined interval if the quiescent distance is greater than a first threshold;
y) increasing the predetermined interval if the quiescent distance is less than a second threshold;
or
z) if the quiescent distance is between the first and second thresholds, making no adjustment to the predetermined interval.

12 more elements

Dependencies are inferred from the claim text.

Implantable medical devices using heuristic filtering in cardiac event detection

Life of this patent

Implantable medical devices using heuristic filtering in cardiac event detection

Life of this patent

Abstract

Claims12