Discrimination of atrial and ventricular signals from a single cardiac lead
First Claim
1. A method of discriminating atrial signals in a heart from ventricular and combined channel heart signals developed by a single endocardial lead system for placement in a heart, comprising the steps of:
- a) sensing ventricular channel signals from an electrode of the endocardial lead system positioned in a ventricle of the heart;
b) sensing combined channel signals from an electrode of the endocardial lead system positioned to receive signals from an atrium of the heart;
c) detecting R waves from the ventricular channel signals;
d) selecting time windows for the ventricular channel signals and combined channel signals based on occurrence of an R wave;
e) estimating a transfer function of the ventricular channel signal to the combined channel during the selected time windows as a measure of a contribution of the R wave to the combined channel signals; and
f) subtracting the estimated transfer function from the combined channel signals to obtain remaining signals, whereby the remaining signals are an approximation of the P waves.
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Abstract
A method and system for discriminating atrial and ventricular signal components from a single heart lead, and for using this information for identifying an arrhythmia condition as being atrial or ventricular in origin. The invention is effective in identifying P waves occurring in complex signal which includes relatively stronger R waves or other ventricular artifacts which mask the P waves. The contribution of the R wave signal to the complex signal is obtained by filtering, time windowing and transfer function estimation, then the R wave estimate is subtracted from the combined signal to leave the P wave. The ratio of P waves to R waves, P--P and R--R intervals, and their ratios to one another and to fixed values can be estimated, and used in a comparison to discriminate between atrial and ventricular arrhythmia, to thereby enable appropriate treatment.
80 Citations
20 Claims
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1. A method of discriminating atrial signals in a heart from ventricular and combined channel heart signals developed by a single endocardial lead system for placement in a heart, comprising the steps of:
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a) sensing ventricular channel signals from an electrode of the endocardial lead system positioned in a ventricle of the heart; b) sensing combined channel signals from an electrode of the endocardial lead system positioned to receive signals from an atrium of the heart; c) detecting R waves from the ventricular channel signals; d) selecting time windows for the ventricular channel signals and combined channel signals based on occurrence of an R wave; e) estimating a transfer function of the ventricular channel signal to the combined channel during the selected time windows as a measure of a contribution of the R wave to the combined channel signals; and f) subtracting the estimated transfer function from the combined channel signals to obtain remaining signals, whereby the remaining signals are an approximation of the P waves. - View Dependent Claims (2, 3, 4)
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5. A method of distinguishing atrial and ventricular arrhythmias in an implantable device including a single endocardial lead system, comprising:
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a) sensing ventricular channel signals from an electrode of the endocardial lead system positioned in a ventricle of a heart; b) sensing combined channel signals from an electrode of said endocardial lead system positioned to receive signals from an atrium of the heart; c) recovering P waves from the combined channel signals by detecting R waves from the ventricular channel signals, estimating a contribution of R waves to the combined channel signals, and subtracting the estimated contribution of R waves from the combined channel signals; d) determining an R wave rate and if the R wave rate is above a threshold value indicating tachycardia; e) comparing a relative frequency of R waves and P waves to determine if a tachyrhythmia condition is atrial or ventricular in origin. - View Dependent Claims (6, 7)
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8. A system for detection of heart arrhythmia, comprising:
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a) a lead system for placement in a heart; b) a ventricular channel subsystem for sensing ventricular signals from an electrode of the lead system which is positioned in a ventricle of the heart; c) a combined channel subsystem for sensing combined channel signals from an electrode of the lead system which is positioned for receiving signals from an atrium of the heart; d) an R wave detector operative to detect R waves from heart signals received by the lead system; e) means for gating selected time windowed intervals of the ventricular channel and combined channel signals based on occurrence of an R wave; f) means for estimating a transfer function of the ventricular channel signal to the combined channel signals during the selected time windowed intervals as a measure of a contribution of the R wave to the combined channel signals; and g) means for subtracting the estimated transfer function from the combined channel signals, whereby remaining signals are an approximation of P waves. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method of distinguishing atrial and ventricular arrhythmias in an implantable device including a single endocardial lead system, comprising:
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a) providing an endocardial lead system positioned in a ventricle of a heart and having a pair of ventricular electrodes respectively at and adjacent a distal end of the lead system for contact in the ventricle, at least one atrial electrode positioned on the lead system at a curved portion therein at a position to mechanically bias the at least one atrial electrode into contact with a wall of an atrium, when the lead system is in its use position; b) sensing ventricular channel signals from the pair of ventricular electrodes of the endocardial lead system; c) sensing combined channel signals from the at least one atrial electrode of the endocardial lead system positioned in the atrium of the heart; d) detecting R waves from the ventricular channel signals, and P waves from the combined channel signals; e) determining if an R wave rate is above a threshold value indicating tachycardia; f) comparing the relative frequency of the R waves and the P waves to determine if a tachyrhythmia condition is atrial or ventricular in origin. - View Dependent Claims (19, 20)
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Specification