SYSTEMS AND METHODS FOR SENSING VECTOR SELECTION IN AN IMPLANTABLE MEDICAL DEVICE

• US 20140296932A1
• Filed: 06/13/2014
• Published: 10/02/2014
• Est. Priority Date: 05/26/2006
• Status: Active Grant

• Current Assignee: Cameron Health Inc (Boston Scientific Corporation)
• Original Assignee: Cameron Health Inc (Boston Scientific Corporation)
• Inventors: Sanghera, Rick, Allavatam, Venugopal
• Granted Patent: US 9,364,677 B2
• Time in Patent Office: Days
• US Class Current: 607/27
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/287 Holders for multiple electrodes, e.g. electrode catheters for electrophysiological study [EPS]
• 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 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: A61N 1/368 comprising more than one electrode co-operating with different heart regions A61N1/3622, A61N1/3627 take precedence
• CPC Class Codes: A61N 1/3704 Circuits specially adapted therefor, e.g. for sensitivity control
• CPC Class Codes: A61N 1/37211 Means for communicating with stimulators
• CPC Class Codes: A61N 1/3918 characterised by shock pathway, e.g. by electrode configuration
• CPC Class Codes: A61N 1/3956 Implantable devices for applying electric shocks to the heart, e.g. for cardioversion

Abstract

Methods and devices for sensing vector analysis in an implantable cardiac stimulus system. In an illustrative example, a first sensing vector is analyzed to determine whether it is suitable, within given threshold conditions, for use in cardiac event detection and analysis. If so, the first vector may be selected for detection and analysis. Otherwise, one or more additional vectors are analyzed. A detailed example illustrates methods for analyzing sensing vectors by the use of a scoring system. Devices adapted to perform these methods are also discussed, including implantable medical devices adapted to perform these methods, and systems comprising implantable medical devices and programmers adapted to communicate with implantable medical devices, the systems also being adapted to perform these methods. Another example includes a programmer configured to perform these methods including certain steps of directing operation of an associated implanted or implantable medical device.

Claims

1. A method of cardiac signal analysis in an implantable cardiac stimulus system having at least first and second sensing electrodes defining a first sensing vector therebetween, the method comprising:

selecting a detection threshold;

capturing a plurality of detected events in which an electrical signal sensed along the first sensing vector exceeds the detection threshold;

analyzing at least one metric related to a signal to noise ratio and amplitude for the plurality of detected events; and

determining whether the first sensing vector is;

suitable for cardiac event detection;

unsuitable for cardiac event detection;

or

available for cardiac event detection.

5. A method of configuring an implantable cardiac therapy device, the cardiac therapy device including a plurality of electrodes usable for sensing cardiac signals and having input circuitry to define a plurality of sensing vectors comprising:

performing the method of claim 1 on a plurality of sensing vectors to generate amplitude scores for the sensing vectors; and

selecting a default sensing vector from the plurality of sensing vectors using at least the amplitude scores.

2. A method of analyzing a biological signal captured by an implantable medical device to configure the implantable medical device to select a sensing vector for sensing cardiac signals, wherein the implantable medical device has an input amplifier having a dynamic range with upper and lower bounds, the input amplifier associated with operational circuitry for analyzing the biological signal, wherein the implantable medical device is configured to operate cooperatively with an associated external programmer, the method comprising:

the operational circuitry comparing the biological signal to a threshold;

the operational circuitry detecting a plurality of detected events at crossings of the threshold by the biological signal, the detected events having peaks;

one of the implantable medical device or the programmer binning peaks related to the detected events into noise bins and R-wave bins;

one of the implantable medical device or the programmer analyzing the amplitudes of the peaks in the R-wave bins to generate an amplitude score, wherein the amplitude score is calculated as follows;

for lower amplitudes at and near the lower bound of the dynamic range, generating a relatively lower amplitude score;

for higher amplitudes at and near the upper bound of the dynamic range, generating a relatively lower amplitude score;

for amplitudes in the middle of the dynamic range, generating a relatively higher amplitude score; and

one of the implantable medical device or the programmer analyzing the amplitude score to determine a quality metric for a sensing vector.

3. The method of claim 2 further comprising:

one of the implantable medical device or the programmer analyzing the amplitudes of the peaks in the R-wave bins and the amplitudes of the peaks in the noise bins to generate a signal-to-noise ratio;

one of the implantable medical device or the programmer converting the signal-to-noise ratio into an SNR score; and

one of the implantable medical device or the programmer combining the SNR score with the amplitude score to generate a sensing vector quality metric.

4. A method of configuring an implantable cardiac therapy device, the cardiac therapy device including a plurality of electrodes usable for sensing cardiac signals and having input circuitry to define a plurality of sensing vectors comprising:

performing the method of claim 2 on a plurality of sensing vectors to generate sensing vector quality metrics for the sensing vectors; and

selecting a default sensing vector from the plurality of sensing vectors using the sensing vector quality metric.

6. A method of selecting a sensing vector for use by an implantable cardiac therapy device, the device having a plurality of electrodes for capturing cardiac electrical signals so as to define a plurality of sensing vectors, the method comprising:

selecting a first vector for quality assessment;

setting a detection threshold to detect signals using the first vector;

collecting a quantity of detected signals occurring when the detection threshold is crossed by a signal received using the first vector, the quantity of signals being identified by first signal peaks associated with a crossing of the detection threshold, at least second signal peaks occurring between first signal peaks, and intervals between the first signal peaks;

placing the first signal peaks and second signal peaks into bins for noise and QRS according to a set of rules, including;

assessing an interval between a pair of first signal peaks and if the interval exceeds a predetermined duration, binning at least one of the first signal peaks as a QRS and a second signal peak occurring during the interval as noise;

if not,

analyzing the interval and at least one other interval to determine whether the intervals are similar and, if not, binning the first signal peak following whichever of the intervals is longer as a QRS and the first signal peak following whichever of the intervals is shorter as Noise;

if not,

reserving for amplitude analysis at least one of the pair of first signal peaks;

determining whether a predetermined number of first peaks are in the QRS bin on the basis of assessing and analyzing intervals, and;

if so, calculating an amplitude value and signal-to-noise ratio for the first vector;

or

if not, further analyzing using an amplitude analysis the first signal peaks which could not be binned into QRS and noise bins using intervals.