Cardiac signal recording using dynamically generated detection thresholds

• US 9,314,178 B2
• Filed: 03/13/2014
• Issued: 04/19/2016
• Est. Priority Date: 03/14/2013
• Status: Active Grant

• Current Assignee: Greatbatch Limited (Greatbatch Incorporated)
• Original Assignee: Greatbach Limited
• Inventors: Katra, Rodolphe, Chakravarthy, Niranjan
• Primary Examiner(s): Holmes, Rex R
• Application Number:
  US14/209,035
• Publication Number:
  US 20140276154A1
• Time in Patent Office: 768 Days
• US Class Current: 1/1
• CPC Class Codes: A61B 2560/0209 adapted for power saving
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/287 Holders for multiple electrodes, e.g. electrode catheters for electrophysiological study [EPS]
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/361 Detecting fibrillation
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia

Abstract

A medical device includes a housing configured for implantation within a body of a patient, and detection circuitry disposed in the housing and coupled to an electrode arrangement. The detection circuitry is configured to sense cardiac signals from the patient. A processor is coupled to the detection circuitry. The processor is configured to compare the cardiac signals to an initial detection threshold, automatically generate an additional detection threshold in response to a predetermined number of the cardiac signals meeting or exceeding the initial detection threshold or a previously generated detection threshold, count each occurrence of a cardiac signal meeting or exceeding each of the respective detection thresholds, and record cardiac signal data only for a cardiac signal that meets or exceeds the highest of the detection thresholds.

Claims

1. A method, comprising:

sensing cardiac signals and comparing the signals to an initial detection threshold;

automatically generating an additional detection threshold in response to a predetermined number of the cardiac signals meeting or exceeding;

the initial detection threshold or a previously generated detection threshold;

concurrently counting each occurrence of a cardiac signal meeting or exceeding each of the detection thresholds; and

recording cardiac signal data only for a cardiac signal of the sensed cardiac signals that meets or exceeds the highest of the detection thresholds.

2. The method of claim 1, wherein automatically generating the additional detection threshold comprises:

automatically generating a plurality of additional detection thresholds;

recording cardiac signal data only for a cardiac signal of the sensed cardiac signals that meets or exceeds the highest of the detection thresholds; and

counting each occurrence of a cardiac signal that meets or exceeds the initial detection threshold and each of the plurality of additional detection thresholds.

3. The method of claim 1, comprising removing the highest of the additional detection thresholds in response to an absence of a cardiac signal of the sensed cardiac signals that meets or exceeds the highest additional detection threshold over a fixed or adaptive time period.

4. The method of claim 3, comprising repeating removing the highest additional detection threshold until only the initial detection threshold is operative for recording cardiac signals.

5. The method of claim 1, wherein the additional detection threshold is offset from the initial detection threshold or the previously generated detection threshold by a fixed value.

6. The method of claim 1, wherein the additional detection threshold is offset from the initial detection threshold or the previously generated detection threshold by a value that can vary over time.

7. The method of claim 1, wherein the predetermined number of cardiac signals needed to meet or exceed the initial detection threshold or a previously generated detection threshold is a fixed or varying integer.

8. The method of claim 1, wherein the additional detection thresholds are indicators of a cardiac status of the patient.

9. The method of claim 8, comprising trending the additional detection thresholds over time.

10. A method, comprising:

(a) setting an initial detection threshold Th₁ and an occurrence threshold X, where X is a positive integer;

(b) sensing cardiac signals from a patient;

(c) recording cardiac signals up to X times in response to sensing cardiac signals that meet or exceed the initial detection threshold Th₁;

(d) automatically generating an additional detection threshold Th₂ in response to sensing X cardiac signals that meet or exceed the initial detection threshold Th₁;

(e) in response to sensing up to Y cardiac signals that meet or exceed the additional detection threshold Th₂;

(i) recording cardiac signals that meet or exceed the additional detection threshold Th₂ up to Y times; and

(ii) automatically generating another additional detection threshold Th₃; and

(f) for each of the respective detection thresholds Th₁, Th₂, and Th₃, counting each occurrence of a cardiac signal that meets or exceeds each respective detection threshold, Th₁, Th₂, and Th₃.

11. The method of claim 10, wherein processes (d) and (e) are repeated in response to sensing a predetermined number of cardiac signals that meet or exceed a previously generated detection threshold.

12. The method of claim 10, comprising removing the highest of the additional detection thresholds in response to an absence of a cardiac signal that meets or exceeds the highest additional detection threshold over a fixed or adaptive time period.

13. The method of claim 10, wherein the additional detection threshold is offset from the initial detection threshold or the previously generated detection threshold by a fixed value or a value that can vary over time.

14. The method of claim 10, comprising trending the additional detection thresholds over time to assess changes in a cardiac status of the patient.

15. The method of claim 10, wherein setting the initial detection threshold or generating an additional detection threshold comprises:

determining a typical range for the cardiac signals specific to the patient; and

setting the initial detection threshold or the additional detection threshold to a value that is beyond the typical range.

16. A medical device, comprising:

a housing configured for implantation within a body of a patient;

detection circuitry disposed in the housing and coupled to an electrode arrangement, the detection circuitry configured to sense cardiac signals from the patient; and

a processor coupled to the detection circuitry, the processor configured to compare the cardiac signals to an initial detection threshold, automatically generate an additional detection threshold in response to a predetermined number of the cardiac signals meeting or exceeding;

the initial detection threshold or a previously generated detection threshold, concurrently count each occurrence of a cardiac signal meeting or exceeding each of the respective detection thresholds, and record cardiac signal data only for a cardiac signal of the sensed cardiac signals that meets or exceeds the highest of the detection thresholds.

17. The device of claim 16, wherein the processor is configured to automatically generate a plurality of additional detection thresholds, record cardiac signal data only for a cardiac signal of the sensed cardiac signals that meets or exceeds the highest of the detection thresholds, and count each occurrence of a cardiac signal of the sensed cardiac signals that meets or exceeds the initial detection threshold and each of the plurality of additional detection thresholds.

18. The device of claim 16, wherein the processor is configured to remove the highest of the additional detection thresholds in response to an absence of a cardiac signal of the sensed cardiac signals that meets or exceeds the highest additional detection threshold.

19. The device of claim 16, wherein the additional detection thresholds are indicators of a cardiac status of the patient, and the processor is configured to trend the additional detection thresholds over time.

20. The device of claim 16, wherein the processor is configured to determine a typical range for the cardiac signals, and set the initial detection threshold or the additional detection threshold to a value that is beyond the typical range.