APPARATUS AND METHOD FOR DETECTION OF LEAD FAILURE IN AN IMPLANTABLE MEDICAL DEVICE
First Claim
1. A method of determining electrocardiogram (ECG) signal quality in an implantable medical device (IMD), the method including the steps of:
- a. sensing at least three ECG signals from at least three spaced electrodes;
b. calculating at least three sensing vectors from the ECG signals, each vector representing the difference between ECG signals from a pair of the spaced electrodes, wherein each vector is obtained from a different one of the pairs of electrodes;
c. calculating a dynamic error signal from the vectors; and
d. adapting the sensing of the ECG signals in dependence on the dynamic error signal.
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Abstract
A method for automatic threshold control and detection of lead failure in an implanted medical device obtains three sensing vectors for measurement of an electrocardiogram signal. A dynamic error signal is determined from the vectors, and may be used to set a detection threshold for insufficient ECG signals, and/or to passively monitor the device for indications of lead failure without performing an impedance measurement. Passive mode operation conserves battery power and enables continuous lead integrity checks. A quality factor may also be determined from the error signal, to indicate whether or not signal measurements are valid with respect to noise levels. If the detection threshold is allowed to decay between successive features of the electrocardiogram, the decay rate may be made adaptive such that it automatically adjusts to changes in heart rate or to changes in amplitude of the electrocardiogram features.
28 Citations
20 Claims
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1. A method of determining electrocardiogram (ECG) signal quality in an implantable medical device (IMD), the method including the steps of:
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a. sensing at least three ECG signals from at least three spaced electrodes; b. calculating at least three sensing vectors from the ECG signals, each vector representing the difference between ECG signals from a pair of the spaced electrodes, wherein each vector is obtained from a different one of the pairs of electrodes; c. calculating a dynamic error signal from the vectors; and d. adapting the sensing of the ECG signals in dependence on the dynamic error signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An implantable medical device (IMD) including:
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A. a casing, and B. at least three spaced electrodes, wherein at least two of the electrodes are connected to the casing via one or more leads, the IMD being configured to; a. sense at least three ECG signals from the electrodes; b. calculate at least three sensing vectors from the ECG signals, each vector representing the difference between ECG signals from a pair of the spaced electrodes, wherein each vector is obtained from a different one of the pairs of electrodes; c. calculate a dynamic error signal from the vectors; and d. adapt the sensing of the ECG signals in dependence on the dynamic error signal.
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17. A method of determining electrocardiogram (ECG) signal quality in an implantable medical device (IMD), the IMD having three or more spaced electrodes, at least two of the electrodes being connected to a casing via one or more leads, each lead having one or more conductors therein, wherein the method includes the steps of:
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a. detecting ECG signals at each of at least three spaced electrodes; b. calculating at least three sensing vectors from three different pairs of the electrodes, wherein each vector represents the potential difference between ECG signals sensed at the electrodes within the vector'"'"'s electrode pair; c. calculating a dynamic error signal representing a difference in potentials between vectors corresponding to electrodes arrayed about a closed path; and d. varying the detection of the ECG signals in dependence on the dynamic error signal. - View Dependent Claims (18, 19, 20)
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Specification