Cardiac event detection over varying time scale
A system for cardiac event detection over varying time scales includes implanted electrical leads forming a portion of an implanted cardiotracker and external equipment including external alarm mechanisms and a physicians programmer. The cardiac event detection system monitors the degradation of a patient's cardiovascular condition from one or more causes. A processor computes the electrical signals of a heart signal parameter's average value over a time period for a multiplicity of heart rate ranges. The electrical signals are stored and information transmitted to external equipment.
1. A device for tracking the cardiovascular condition of a human patient the system including:
at least two implanted electrodes that are positioned within the human patient to sense the electrical signal from the patient's heart, the electrical signal consisting of a multiplicity of beats;
a memory;
a processor configured to
(a1) compute from the electrical signal a heart signal parameter value associated with each of the multiplicity of beats,
(a2) compute a heart rate value associated with each of the multiplicity of beats,
(a3) for each of the multiplicity of beats, select one of a plurality of histograms to update according to the associated heart rate wherein each histogram includes a plurality of histogram bins,
(a4) for each of the multiplicity of beats, increment one of the plurality of histogram bins within the selected histogram corresponding to the beat, wherein the selection of the histogram bin to be incremented is dependent on the computed value of the heart signal parameter,
(a5) compute from the plurality of histogram bins a heart parameter's average value over a time period for each of a multiplicity of heart rate ranges, thereby generating a multiplicity of average values;
(b) store the multiplicity of average values in the memory according to both time period and heart rate; and,
(c) repeat (a1)-(a5), and (b) for a multiplicity of time periods, thereby generating, for each heart rate range, a time series of average values of the parameter.
2. The device of claim 1 further including a transmitter for sending to an external device the time series of average values for each heart rate bin.
3. The device of claim 1 wherein the processor is further configured to analyze at least one of the time series of average values to generate a trend curve that describes changes in the average values over time.
4. The device of claim 3 further including an alarm, and wherein the processor is further configured to generate an alarm if the trend of the average values indicates a pathological condition.
5. The device of claim 3 wherein the trend is based on a moving average of the time series of average values.
6. The device of claim 1 wherein the processor is further configured to store heart signal parameter value histograms for each of the multiplicity of heart rate ranges, and wherein each of the multiplicity of average values is determined according to data in a corresponding histogram.
7. The device of claim 1 wherein the heart signal parameter is ST segment deviation.