Medical device for Atrial fibrillation prediction
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Publication Number
US-9026207-B2
Publication Date
2015-05-05
Expiration Date
Abstract
In a device and a method for providing correlated measures for predicting potential occurrence of atrial fibrillation, an impedance of the patient is measured to obtain impedance information; cardiogenic data is determined from the information; respiratory data is determined from the information; at least one hemodynamic measure is calculated from the cardiogenic data and at least one apnea measure is calculated from the respiratory data; the hemodynamic and apnea measures are correlated such that the correlated measures can be utilized for predicting potential occurrence of atrial fibrillation.
Core Innovation
The invention relates to an implantable medical device that predicts atrial fibrillation by measuring impedance of a patient using electrodes of medical leads and deriving cardiogenic impedance data and respiratory impedance data. The device includes an impedance measuring unit that measures patient impedance and provides impedance information corresponding to the measured impedance, which is supplied to a cardiogenic impedance determining unit and to a respiration impedance determining unit.
The device determines at least one hemodynamic measure using the cardiogenic impedance data and at least one apnea measure using the respiratory impedance data. The hemodynamic measure and the apnea measure are correlated over a time period to obtain a relationship between a development of the hemodynamic measure and a development of the apnea measure, and the correlating unit calculates an atrial fibrillation prediction value as a function of the correlation.
In further implementations, the hemodynamic measure is determined as a time derivative of a cardiogenic impedance curve corresponding to impedance change during a cardiac cycle, and the cardiogenic impedance curve is synchronized with an ECG QRS complex by detecting the QRS complex and using a time window following the QRS. The apnea measure is determined using breath detection derived from a respiratory impedance curve by integrating the respiratory impedance curve to obtain an area value under the curve, and by counting apneic events such that the number is increased when no second breath is detected within a time window of predetermined length following a first breath.
Claims Coverage
Independent claim clm-00001 defines an implantable medical device for predicting atrial fibrillation based on a correlation between a hemodynamic measure derived from cardiogenic impedance and an apnea measure derived from respiratory impedance. The inventive concept has 6 inventive features, with dependent claim refinements describing specific definitions of the hemodynamic measure, breath/apnea detection logic, synchronization to ECG QRS, and sleep-state-triggered actions.
Impedance-based cardiogenic and respiratory data acquisition
The impedance measuring unit measures an impedance of the patient via at least two electrodes and provides impedance information corresponding to the measured impedance, which is received to determine cardiogenic impedance data and respiratory impedance data.
Hemodynamic and apnea measures from impedance data
The calculation unit determines at least one hemodynamic measure using the cardiogenic impedance data and determines at least one apnea measure using the respiratory impedance data.
Time-period correlation to generate an atrial fibrillation prediction value
The correlating unit calculates an atrial fibrillation prediction value as a function of a correlation between the hemodynamic and apnea measures, the correlation constituting a relationship, over a time period, between a development of the hemodynamic and apnea measures.
ECG-synchronized cardiogenic processing for time-derivative hemodynamics
At least one hemodynamic measure is determined as a time derivative of a cardiogenic impedance curve corresponding to impedance change during a cardiac cycle, and the cardiogenic impedance curve is synchronized with a detected ECG QRS complex using a time window following the QRS complex.
Integration-based respiratory impedance breath detection and apnea event counting
The apnea measure is determined from breath detection based on integrating a respiratory impedance curve to obtain an area value under the impedance curve, and apnea is measured as a number of apneic events increased when no second breath is detected within a time window of predetermined length following a first breath.
Sleep-state information to support predetermined actions for correlation use
A sleep indication unit detects a sleeping state to generate sleep status information that is received by at least one component of the device to execute a predetermined action.
Across the independent claim and its key refinements, the coverage centers on calculating a hemodynamic measure and an apnea measure from impedance-based cardiogenic and respiratory data and producing an atrial fibrillation prediction value from a time-period correlation between the development of those measures. Dependent refinements further specify hemodynamics as a time-derivative of a cardiogenic impedance curve synchronized to ECG QRS, apnea as integration-based breath detection with time-windowed apneic-event counting, and optional sleep-status-triggered actions.
Stated Advantages
Documented Applications
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