Multi-vector sensing in cardiac devices with signal combinations

• US 10,299,688 B2
• Filed: 10/19/2016
• Issued: 05/28/2019
• Est. Priority Date: 10/23/2015
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Brisben, Amy Jean, Allavatam, Venugopal, Siejko, Krzysztof Z., Mahajan, Deepa, Wika, Kevin G., Herrmann, Keith L., Hahn, Stephen J.
• Primary Examiner(s): Porter, Allen
• Application Number:
  US15/297,588
• Publication Number:
  US 20170113040A1
• Time in Patent Office: 951 Days
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/283 Invasive
• 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 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/327 Generation of artificial ECG signals based on measured signals, e.g. to compensate for missing leads
• CPC Class Codes: A61B 5/341 Vectorcardiography [VCG]
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/35 by template matching
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/364 Detecting abnormal ECG interval, e.g. extrasystoles, ectopic heartbeats
• CPC Class Codes: A61B 5/366 Detecting abnormal QRS complex, e.g. widening
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: A61B 5/6869 Heart
• CPC Class Codes: A61B 5/72 Signal processing specially adapted for physiological signals or for diagnostic purposes character recognition, recognising digital ink, document-oriented image-based pattern recognition G06V30/00; recognition or understanding of postal images G06V30/424
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61N 1/046 Specially adapted for shock therapy, e.g. defibrillation
• CPC Class Codes: A61N 1/05 for implantation or insertion into the body, e.g. heart electrode A61N1/06 takes precedence
• CPC Class Codes: A61N 1/0563 : specially adapted for defibrillation or cardioversion
• CPC Class Codes: A61N 1/3622 : comprising two or more electrodes co-operating with different heart regions
• CPC Class Codes: A61N 1/3625 : External stimulators
• CPC Class Codes: A61N 1/36514 : controlled by a physiological quantity other than heart potential, e.g. blood pressure controlled by two or more physical parameters A61N1/36585
• CPC Class Codes: A61N 1/3704 : Circuits specially adapted therefor, e.g. for sensitivity control
• CPC Class Codes: A61N 1/3925 : Monitoring; Protecting
• CPC Class Codes: A61N 1/3956 : Implantable devices for applying electric shocks to the heart, e.g. for cardioversion
• CPC Class Codes: A61N 1/3987 : characterised by the timing or triggering of the shock

Abstract

Methods and devices for combining multiple signals from multiple sensing vectors for use in wearable or implantable cardiac devices. Signals from multiple vectors may be combined using weighting factors and/or by conversion to different coordinate systems than the original inputs, which may or may not be normalized to patient anatomy. Signals from multiple sensing vectors may be combined prior to or after several analytical steps or processes including before or after filtering, and before or after cardiac cycle detection. Cardiac cycle detection information may be combined across multiple sensing vectors before or after analysis of individual vectors for noise or overdetection. Cardiac cycle detection information may also be combined across multiple sensing vectors to identify noise and/or overdetection.

Claims

1. A cardiac rhythm management device having operational circuitry for analyzing cardiac signals using a least first and second cardiac sensing vectors and first and second sensing channels, wherein the operational circuitry is configured to:

calculate at least first and second weighting factors for the at least first and second sensing vectors;

apply the first weighting factor to modify signals sensed with the first sensing vector;

apply the second weighting factor to modify signals sensed with the second sensing vector;

produce a combined signal by combining the signals from the first and second sensing vectors together, as modified by the weighting factors;

compare the combined signal to a time-changing detection threshold to detect cardiac cycles;

calculate a rate based on the detected cardiac cycles;

determine whether a treatable cardiac state is occurring based on the rate;

deliver cardiac electrical therapy if it is determined that the treatable cardiac state is occurring; and

on a triggered or continuous basis, recalculate the weighting factors.

2. The device of claim 1 wherein the operational circuitry is configured to calculate a phase factor to apply to delay one of the first or second cardiac signal vectors for the combining step.

3. The device of claim 1 wherein the operational circuitry is configured to apply filtering to the first and second sensing vectors prior to applying the weighting factors.

4. The device of claim 1 wherein the operational circuitry is configured to apply filtering to the first and second signals as modified by the weighting factors.

5. The device of claim 1, wherein the operational circuitry is further configured to:

sample the combined signal for use in the cardiac cycle detection.

6. The device of claim 1 wherein the operational circuitry is configured to perform parallel processing of at least first and second sampled and conditioned data streams, wherein the first data stream comes from one of the at least first and second sensing vectors, as modified by the weighting factors, and the second data stream comes from the combined signal of the first and second sensing vectors.

7. The device of claim 6 wherein operational circuitry is configured for switching the first data stream between the first and second sensing vectors, wherein the operational circuitry is further configured to analyze the first data stream to update one or more of the weighting factors over time.

8. The device of claim 7 wherein the operational circuitry is further configured to:

periodically switch from the first sensing vector to the second sensing vector for analysis in the second data stream at predefined intervals; and

occasionally switch from the first sensing vector to the second sensing vector for analysis in the second data stream in response to a triggering event.

9. The device of claim 6 wherein the operational circuitry is configured to analyze the first and second data streams for noise and if noise is found in the first data stream but not in the second data stream, modify a corresponding weighting value for whichever of the sense vectors is in the first data stream at the time of the noise to underweight that data stream.

10. The device of claim 1 wherein the operational circuitry is configured such that:

the weighting factors are comprised of an ordered series of individual weighting multipliers having at least first and second values;

the step of applying the weighting factors is performed by determining that a new cardiac cycle has been detected, and then beginning with a first of the ordered series of individual weighting multipliers, multiplying the weighting multipliers by individual signal samples from the sensing vector.

11. A method using a cardiac rhythm management device having operational circuitry for analyzing cardiac signals using a least first and second cardiac sensing vectors and first and second sensing channels, the method comprising:

calculating at least first and second weighting factors for the at least first and second sensing vectors;

applying the first weighting factor to modify signals sensed with the first sensing vector;

applying the second weighting factor to modify signals sensed with the second sensing vector;

producing a combined signal by combining the signals from the first and second sensing vectors together, as modified by the weighting factors;

using the combined signal to detect cardiac cycles;

calculating a rate based on the detected cardiac cycles;

determining whether a treatable cardiac state is occurring based on the rate;

delivering cardiac electrical therapy if it is determined that the treatable cardiac state is occurring; and

on a triggered or continuous basis, recalculating the weighting factors.

12. The method of claim 11 further comprising calculating a phase factor to apply to delay one of the first or second cardiac signal vectors for the combining step.

13. The method of claim 11 further comprising

sampling the combined signal for use in the cardiac cycle detection.

14. The method of claim 11 further comprising performing parallel processing of at least first and second sampled and conditioned data streams, wherein the first data stream comes from one of the at least first and second sensing vectors, as modified by the weighting factors, and the second data stream comes from the combined signal of the first and second sensing vectors.

15. The method of claim 14 further comprising:

switching the first data stream between the first and second sensing vectors;

analyzing the first data stream to update one or more of the weighting factors over time;

periodically switching from the first sensing vector to the second sensing vector for analysis in the second data stream at predefined intervals; and

occasionally switching from the first sensing vector to the second sensing vector for analysis in the second data stream in response to a triggering event.

16. The method of claim 14 further comprising analyzing the first and second data streams for noise and if noise is found in the first data stream but not in the second data stream, modifying a corresponding weighting value for whichever of the sense vectors is in the first data stream at the time of the noise to underweight that data stream.

17. The method of claim 11 wherein:

the weighting factors are comprised of an ordered series of individual weighting multipliers having at least first and second values;

the step of applying the weighting factors is performed by determining that a new cardiac cycle has been detected, and then beginning with a first of the ordered series of individual weighting multipliers, multiplying the weighting multipliers by individual signal samples from the sensing vector.

18. The method of claim 11 further comprising filtering to the first and second sensing vectors prior to applying the weighting factors.

19. The method of claim 11 further comprising filtering to the first and second signals as modified by the weighting factors.