System and method for reconstructing cardiac activation information
Inventors
Narayan, Sanjiv • Briggs, Carey Robert • Sehra, Ruchir
Assignees
Topera Inc • Office of General Counsel of VA • University of California San Diego UCSD
Publication Number
US-9050006-B2
Publication Date
2015-06-09
Expiration Date
2031-08-24
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Abstract
An example system and method of reconstructing cardiac activation information are disclosed. An analysis signal and a reference signal are processed to determine whether there is a first point of change in a first selected-order derivative of the analysis signal with respect to a first selected-order derivative of the reference signal above a first threshold. The analysis signal and the reference signal are processed to determine whether there is a second point of change in a second selected-order derivative of the analysis cardiac signal with respect to a second selected-order derivative of the reference cardiac signal above a second threshold. An activation onset time is assigned in the analysis cardiac signal at a point based on a mathematical association of the first point of change and the second point of change to define cardiac activation indicating a beat in the analysis cardiac signal.
Core Innovation
The invention provides a system and method for reconstructing cardiac activation information associated with heart rhythm disorders, particularly complex rhythm disorders such as atrial fibrillation, ventricular tachycardia, and ventricular fibrillation. It involves processing an analysis cardiac signal and a reference cardiac signal to detect points of change in selected-order derivatives of these signals above defined thresholds, and assigning activation onset times based on a mathematical association of these points of change. This reconstruction facilitates identifying cardiac activation indicating beats in the analysis signal.
Heart rhythm disorders represent significant morbidity and mortality, with complex disorders being difficult to treat due to the inability to accurately identify activation onset patterns and their sources. Prior systems failed to identify earliest locations of activation onsets in complex rhythm disorders because activation onset patterns are continuously changing and lack identifiable start or end points. The invention addresses this problem by providing a relatively few step method to reconstruct activation information even amidst virtually indiscernible activation patterns, enabling determination and treatment of the disorder source with expediency.
Claims Coverage
The claims include three independent claims covering a method of reconstructing cardiac activation information, a system configured to perform such reconstruction, and a method of treating a cardiac rhythm disorder. The inventive features center on processing selected-order derivatives of analysis and reference cardiac signals, detecting points of change above thresholds, and assigning activation onset times based on mathematical associations of these points of change.
Processing of selected-order derivatives to detect points of change above thresholds
The method and system process an analysis cardiac signal and a reference cardiac signal to determine whether first and second points of change in first and second selected-order derivatives, respectively, of the analysis signal with respect to those of the reference signal are above respective first and second thresholds.
Assigning activation onset times based on mathematical association of points of change
Activation onset times in the analysis cardiac signal are assigned at points based on a mathematical association of the detected first and second points of change to define cardiac activation indicating a beat, conditioned on at least one point of change exceeding its threshold.
Mathematical association comprising averages or selection based on difference values or thresholds
The mathematical association can be an average of points of change representing majorities or pluralities of reference signals within a predetermined time interval (±5 ms), or a selection of one point of change based on computed difference values relative to thresholds or based on the highest selected-order derivative exceeding its threshold.
Use of composite cardiac signal for enhanced point of change determination
Composite cardiac signals, formed by subtracting or adding analysis and reference signals, are used to determine ratio values at multiple points. Points with largest ratio values are selected as points of change in the analysis signal for first and second selected-order derivatives.
Threshold values set above noise level to distinguish meaningful points of change
The first and second thresholds are selected to be above noise levels associated with the cardiac signals to distinguish significant points of change from noise or signals originating from other physiological or electronic sources.
Catalog matching for signals lacking points of change above thresholds
If no points of change exceed thresholds, characteristics of the analysis cardiac signal are matched to those in a catalog of reference cardiac signals to assign activation onset times based on matched signals.
Iterative processing of multiple pairs of cardiac signals to reconstruct activation pattern
The method and system iteratively select pairs of analysis and reference signals from a plurality of cardiac signals, perform processing and assigning activation onset times to define multiple cardiac activations, and reconstruct a cardiac activation pattern indicating the source of a cardiac rhythm disorder.
Treatment method utilizing reconstructed cardiac activation pattern
The treatment method involves accessing multiple cardiac signals, reconstructing activation onset times via processing of derivatives as described, reconstructing a cardiac activation pattern to locate the source of the disorder, and treating cardiac tissue at the identified source to suppress or eliminate the rhythm disorder.
The claims collectively cover methods and systems for detecting points of change in selected-order derivatives of cardiac signals above thresholds, mathematically associating these points to assign activation onset times, utilizing composite signals and catalog matching, iteratively processing multiple signal pairs to reconstruct cardiac activation patterns, and treating cardiac rhythms based on such reconstructions.
Stated Advantages
Ability to reconstruct cardiac activation information enabling determination and treatment of heart rhythm disorder sources.
Capability to perform reconstruction rapidly during sensing, allowing immediate treatment.
Reduction in complexity and number of steps compared to prior methods, improving accuracy in complex rhythm disorders.
Documented Applications
Reconstruction of cardiac activation information associated with heart rhythm disorders, particularly complex disorders such as atrial fibrillation, ventricular tachycardia, and ventricular fibrillation.
Treatment of cardiac rhythm disorders by reconstructing cardiac activation patterns to identify and ablate or otherwise treat the source of the disorder.
Application to biological rhythm disorders beyond cardiac, including neurological seizures, esophageal spasms, bladder instability, and irritable bowel syndrome.
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