Histogram based generation of cardiac state detection thresholds

• US 9,005,130 B2
• Filed: 12/10/2013
• Issued: 04/14/2015
• Est. Priority Date: 11/26/2003
• Status: Expired due to Fees

• Current Assignee: Angel Medical Systems, Inc.
• Original Assignee: Angel Medical Systems, Inc.
• Inventors: Fischell, David R., Fischell, Robert E., Harwood, Jonathan, Johnson, Steven R.
• Primary Examiner(s): Koharski, Christopher D
• Assistant Examiner(s): Patel, Natasha
• Application Number:
  US14/101,499
• Publication Number:
  US 20140107514A1
• Time in Patent Office: 490 Days
• Field of Search: 600/508, 600/516, 600/518
• US Class Current: 600/508
• CPC Class Codes: A61B 5/0006 ECG or EEG signals
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/02455 provided with high/low alarm devices
• CPC Class Codes: A61B 5/283 Invasive
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/333 Recording apparatus specially adapted therefor
• CPC Class Codes: A61B 5/339 Displays specially adapted therefor
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/366 Detecting abnormal QRS complex, e.g. widening
• CPC Class Codes: A61B 5/413 Monitoring transplanted tissue or organ, e.g. for possible rejection reactions after a transplant
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: A61B 5/746 Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B
• CPC Class Codes: A61N 1/025 Digital circuitry features of electrotherapy devices, e.g. memory, clocks, processors
• CPC Class Codes: A61N 1/37211 Means for communicating with stimulators
• CPC Class Codes: A61N 1/37247 User interfaces, e.g. input or presentation means

Abstract

A method for tracking cardiac conditions is disclosed. An electrical signal from a patient'"'"'s heart is sensed. A heart signal parameter value and an associated heart rate value are computed from the electrical signal. Based on the heart rate value, one of a plurality of histograms stored in a histogram memory is updated with the heart signal parameter value. After a data collection time period has elapsed, a statistical value of the heart signal parameter is computed from the selected histogram. A detection threshold for abnormal values of the heart signal parameter is then computed based on the statistical value.

Claims

1. A method for tracking the cardiovascular condition of a human patient, including the steps of:

(a) sensing an electrical signal from the patient'"'"'s heart, the electrical signal comprising a multiplicity of beats;

(b) computing from the electrical signal a heart signal parameter value associated with at least one of the multiplicity of beats;

(c) computing a heart rate value based on the at least one of the multiplicity of beats;

(d) selecting one of a plurality of histograms stored in a histogram memory to update according to the heart rate value, wherein each histogram includes a plurality of histogram bins;

(e) during a data collection time period, incrementing one of the plurality of histogram bins, wherein the selection of the histogram bin to be incremented is dependent on the computed value of the heart signal parameter;

(f) after the end of the data collection time period, calculating a statistical value of the heart signal parameter from the selected histogram;

(g) storing the statistical value in memory; and

(h) calculating a detection threshold for abnormal values of the heart signal parameter based on the statistical value.

2. The method of claim 1 wherein the statistical value is the mean value of the heart signal parameter.

3. The method of claim 1 wherein the statistical value is the median value of the heart signal parameter.

4. The method of claim 1 further including the step of calculating the standard deviation of the value of the heart signal parameter value, and wherein the detection threshold is based on the mean plus the standard deviation.

5. The method of claim 1 wherein the data collection time period is 24 hours.

6. The method of claim 1 wherein the histogram memory is within an implantable device.

7. The method of claim 6 further including the step of transmitting histogram data from the implantable device to an external programmer, and wherein the detection threshold is calculated by a programmer.

8. The method of claim 1 further including the step of counting the number of beats characterized by values of the heart signal parameter that exceed the detection threshold.

9. The method of claim 1 selection of the histogram bin to be incremented is dependent on only the computed value of the heart signal parameter for a single beat.