Apparatus and method for detecting myocardial ischemia using analysis of high frequency components of an electrocardiogram
Inventors
Amit, Guy • Luria, Oded • Toledo, Eran • Granot, Yair • Ben-David, Tamir
Assignees
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Publication Number
US-8626275-B1
Publication Date
2014-01-07
Expiration Date
Abstract
ECG apparatus comprises an ECG input for obtaining ECG signals; a high frequency analyzer configured for obtaining high frequency QRS components from a QRS complex within said ECG signals and identifying therein at least one reduced amplitude zone—RAZ—present within a given QRS complex; and a RAZ quantifier configured for obtaining a quantification of said at least one RAZ region within said QRS complex.
Core Innovation
An ECG-based ischemia detection system obtains wideband ECG signals and extracts high frequency QRS components from a QRS complex within the ECG signals. A low frequency envelope around the high frequency QRS components is computed, and a reduced amplitude zone, or RAZ, is identified within the envelope and present within the given QRS complex. The invention quantifies the RAZ region within the QRS complex so that the quantification is proportional to an area of the RAZ within the QRS complex.
The invention defines a High Frequency Morphology Index, or HFMI, based on RAZ quantification, where the index is proportional to RAZ area, including a ratio of RAZ basin area to envelope area. A noise cancellation approach is described by aligning successive beats for extraction and averaging of high-frequency QRS morphology features, and multi-lead processing is described with statistical aggregation, including 12-lead averaging of highest lead values.
Myocardial ischemia is indicated when the HFMI or RAZ quantification is relatively high, and falling HFMI over time can indicate successful intervention, including spontaneous reperfusion. The partial content also describes possible implantable implementation of the system and example clinical study results showing higher HFMI at admission compared to post-reperfusion, supporting diagnostic and monitoring use.
Claims Coverage
The independent claims are an ECG apparatus and an ECG method family that cover extracting high-frequency QRS components, forming a low-frequency envelope, identifying reduced amplitude zones, and quantifying RAZ size or area to compute an index proportional to RAZ area or an area ratio. Across the provided independent claims, the inventive features include the HFQRS, envelope, and RAZ extraction and quantification, with alternative definitions of RAZ area relative to envelope local minimum and flanking maxima or by extrapolation and area difference. Additional claim coverage in the provided material includes noise cancellation via aligning successive heartbeats, multi-lead statistical aggregation with a 12-lead averaging rule of highest lead quantifications, and ischemia indication and trend interpretation.
Wideband ECG signal processing with high frequency analyzer extracting HFQRS and low frequency envelope
An ECG apparatus obtains wideband ECG signals, obtains high frequency QRS components from a QRS complex, and obtains a low frequency envelope around the high frequency QRS components.
Reduced amplitude zone identification within low frequency envelope
The apparatus identifies within the envelope at least one reduced amplitude zone, or RAZ, present within a given QRS complex.
RAZ quantification to compute an index proportional to RAZ area
A RAZ quantifier obtains a quantification of the at least one RAZ region within the QRS complex, wherein the quantification is used to compute an index that is proportional to an area of the RAZ within the QRS complex.
ECG method with HFQRS extraction, low frequency envelope, and RAZ quantification proportional to RAZ size
An ECG method obtains ECG signals, obtains high frequency QRS components, obtains a low frequency envelope around the high frequency components, identifies at least one reduced amplitude zone, or RAZ, within a given QRS complex, and obtains a quantification of the at least one RAZ region within the QRS complex, wherein the quantification is proportional to a size of the RAZ within the QRS complex.
RAZ quantification as ratio of RAZ area to envelope area
An ECG method obtains a quantification of the at least one RAZ region by obtaining a ratio between an area of the at least one RAZ and an area within the envelope.
Alternative definitions of RAZ area relative to envelope local minimum and flanking maxima
An ECG method obtains a quantification where the area of the at least one RAZ is an area over a local minimum in the envelope between two flanking maxima of the envelope, or the area is measured by connecting the respective flanking maxima, or under a horizontal line at a height of one of the flanking maxima, or by connecting peaks of the flanking maxima, or by estimating an expected peak without RAZ by extrapolation and calculating a difference in areas.
The provided independent claims focus on detecting and quantifying reduced amplitude zones within a low frequency envelope formed around extracted high frequency QRS components, using RAZ area or area-proportional quantification to compute an index. Additional claim direction in the provided material further supports noise cancellation through alignment of successive beats, multi-lead statistical aggregation, including a 12-lead averaging rule of highest lead quantifications, and using relatively high RAZ quantification and falling RAZ quantification over time for ischemia indication and monitoring.
Stated Advantages
Indicates myocardial ischemia when a relatively high RAZ quantification is present.
Falling RAZ quantification over time indicates successful interventions.
Provides an index proportional to RAZ area within the QRS complex.
Documented Applications
Diagnostic use: myocardial ischemia detection based on relatively high HFMI or RAZ quantification, including acute coronary syndrome context such as ST-elevation MI as described in the partial content.
Monitoring use: tracking changes over time where falling HFMI or RAZ quantification indicates successful intervention, including spontaneous reperfusion, with example clinical study results described in the partial content.
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