System and method for reconstructing cardiac activation information
Inventors
Narayan, Sanjiv • Briggs, Carey Robert
Assignees
US Department of Veterans Affairs • Topera Inc • University of California San Diego UCSD
Publication Number
US-9055878-B2
Publication Date
2015-06-16
Expiration Date
2031-08-24
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Abstract
An example system and method of reconstructing cardiac activation information are disclosed. In accordance therewith, there are accessed pairs of cardiac signals out of a plurality of cardiac signals obtained from a patient. The pairs have a first cardiac signal that is common among the pairs and second cardiac signals that are different among the pairs. The first cardiac signal and the second cardiac signals of the pairs are processed to determine whether there are points of change in the first cardiac signal at which a derivative of the first cardiac signal diverges with respect to derivatives of the second cardiac signals above a threshold. An activation onset time is assigned at a point in the first cardiac signal based on correspondence of the points of change to define a cardiac activation indicating a beat if the points of change are in the first signal.
Core Innovation
The invention provides a system and method for reconstructing cardiac activation information, particularly activation onset times, from multiple cardiac signals obtained from a patient. This is achieved by accessing pairs of cardiac signals where one signal is common among pairs and the other differs, then processing these pairs to detect points in the common signal where its derivative diverges from derivatives of the other signals above a threshold. Activation onset times are then assigned to these points to define cardiac activations indicating beats.
The problem being solved relates to the difficulty of diagnosing and treating complex heart rhythm disorders such as atrial fibrillation (AF), ventricular tachycardia (VT), and ventricular fibrillation (VF). Prior systems and methods were unable to accurately identify activation onsets in complex, multi-deflection cardiac signals, hindering locating the cause of the disorder and effective treatment. Existing techniques were effective mainly for simple rhythm disorders where activation patterns are consistent, but failed in complex disorders with continuous and variable activation patterns that change beat to beat.
The disclosed invention addresses these issues by reconstructing activation onsets even in complex signals with multiple deflections and beat-to-beat variability. By systematically comparing derivatives of paired cardiac signals and identifying points of significant change, the invention enables determination of activation onset times that were previously indiscernible. This reconstructed information facilitates identification of the source of heart rhythm disorders, thus enabling targeted and potentially curative treatments.
Claims Coverage
The patent claims include four independent claims outlining both a method and a system for reconstructing cardiac activation information. The main inventive features involve accessing pairs of cardiac signals, processing their derivatives to identify points of change, and assigning activation onset times based on these points.
Reconstructing cardiac activation information by processing pairs of cardiac signals
Accessing pairs of cardiac signals from a plurality with a common first signal and different second signals; processing the first and second signals to determine points where the derivative of the first signal diverges from those of the second signals above a threshold; and assigning activation onset times at these points to define cardiac activations indicating beats.
Determination of points of change using derivatives and significance thresholds
The method and system determine divergence points using zero or higher order derivatives and calculate significance values based on slopes, amplitude, timing, and shape. Points of change are identified by comparing these values to a threshold higher than noise levels.
Use of composite cardiac signals to enhance point of change detection
Forming a composite signal from the pair of signals (e.g., subtracting or adding signals) and determining ratio values at multiple points to select as points of change those having the largest ratio values, improving differentiation of local activation from far-field signals or noise.
Assigning activation onset times by averaging or weighting across multiple reference signals
Final activation onset times for a signal are determined by averaging activation onset times from multiple reference signals, averaging selected activation onset times within a time interval, calculating a significance-weighted center of mass, or defining predominant activation onset direction relative to sensor locations.
Iterative processing of multiple cardiac signals to reconstruct activation patterns
Iteratively selecting first cardiac signals from the plurality, accessing respective pairs with different second signals, performing processing and assignment of activation onsets for multiple beats, and reconstructing a cardiac activation pattern to indicate the source of a cardiac rhythm disorder.
Matching signals to a catalog of reference cardiac signals when no significant points of change are found
If no point of change exceeds the threshold, the first cardiac signal is matched to characteristics of reference signals in a catalog, and activation onset times are assigned based on the matched reference signal.
The claims broadly cover methods and systems that access and process paired cardiac signals to identify and assign activation onset times based on derivative divergence, including enhancements such as composite signals, averaging approaches, catalog matching, and iterative application to reconstruct activation patterns for locating sources of heart rhythm disorders.
Stated Advantages
Enables reconstruction of cardiac activation information in complex heart rhythm disorders where previous methods failed.
Facilitates rapid determination of the cause or source of heart rhythm disorders to enable timely and targeted treatment.
Reduces complexity and steps required to reconstruct activation onsets compared to prior systems.
Allows for real-time or near real-time processing while sensors are used in or near the patient.
Supports treatment decisions such as targeted ablation to suppress or eliminate cardiac rhythm disorders based on reconstructed activation patterns.
Documented Applications
Diagnosis and treatment of complex heart rhythm disorders including atrial fibrillation, ventricular tachycardia, and ventricular fibrillation.
Use in cardiac catheterization procedures involving catheters with arrays of sensors to collect cardiac signals.
Facilitation of targeted cardiac tissue ablation to treat and potentially cure heart rhythm disorders.
Reconstruction of biological activation information for other biological rhythm disorders such as neurological seizures, esophageal spasms, bladder instability, and irritable bowel syndrome.
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