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-9468387-B2
Publication Date
2016-10-18
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 identify 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. 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.
Core Innovation
The invention provides a system and method for reconstructing cardiac activation information, specifically activation onset times, from cardiac signals obtained from a patient. It involves accessing pairs of cardiac signals where one signal is common among the pairs and the other signals vary, processing these to identify points where the derivative of the common signal diverges relative to the derivatives of the differing signals, and assigning activation onset times based on the correspondence of these points, thereby defining a cardiac activation indicating a heartbeat.
The problem addressed is the difficulty in identifying activation onsets in complex heart rhythm disorders, such as atrial fibrillation (AF), ventricular tachycardia (VT) and ventricular fibrillation (VF), where beat-to-beat activation patterns change and exhibit complex signals with multiple deflections. Existing methods cannot reliably determine earliest activation points, hindering locating sources of arrhythmias for treatment. This limits effective treatment by ablation since current tools cannot accurately localize and characterize the causes of such disorders.
The invention overcomes these limitations by reconstructing cardiac activation information amidst complex and overlapping deflections in electrogram signals. It utilizes comparing derivatives of paired cardiac signals recorded by multiple sensors, assessing divergence points that indicate local activation distinct from far-field or noise. By aggregating activation onset times from multiple paired comparisons, the system reconstructs a cardiac activation pattern indicative of the source or cause of the rhythm disorder, enabling targeted and potentially curative treatment. The method can be implemented by a computing system processing signals collected by catheters with multiple sensors inside or near the heart.
Claims Coverage
The patent contains two independent claims, covering a method and a system for reconstructing cardiac activation information. The claims focus on processing cardiac signals to identify activation onset times based on derivative divergence and correspondence among points of change.
Accessing pairs of cardiac signals with a common first signal and differing second signals
The invention involves accessing multiple pairs of cardiac signals obtained from a patient, where each pair includes a first cardiac signal common to all pairs and distinct second cardiac signals.
Processing derivatives of cardiac signals to identify divergence points
Processing the first cardiac signal and the various second cardiac signals to identify points of change where the derivative of the first signal diverges relative to the derivatives of the second signals, indicating potential activation onsets.
Assigning activation onset time based on correspondence among points of change
Determining correspondence among identified points of change across pairs and assigning activation onset times at points in the first cardiac signal to define cardiac activations representing beats.
Determining activation onset through averaging, majority selection, center-of-mass, or predominant direction
Refining activation onset assignment through averaging all activation times, averaging majority timings within a set interval, calculating a weighted center-of-mass of activation times by significance, or defining activation onset based on predominant direction relative to sensor locations.
Use of zero order, first, second or higher order derivatives and combinations thereof
Utilizing various orders of derivatives of the cardiac signals for identifying divergence points between signal pairs.
Obtaining cardiac signals contemporaneously via multiple sensors
Accessing the cardiac signals using multiple sensors obtaining signals contemporaneously from the patient, with the first and second signals coming from different sensors.
Optional use of composite signals for enhanced processing
Forming a composite cardiac signal by combining the first and second signals (e.g., subtracting one from the other) and determining ratio values of derivatives to more precisely identify points of change with largest divergence ratios.
Noise thresholding to distinguish true activations from noise or far-field signals
Considering points of change only above a noise level to exclude signals arising from other biological systems or electronic interference, thus enhancing detection accuracy.
Iterative processing for multiple activations and multiple signals to reconstruct cardiac activation patterns
Iteratively selecting first signals and pairing with various second signals, processing and assigning multiple activation onsets to reconstruct cardiac activation patterns indicative of the source of a rhythm disorder.
Displaying reconstructed cardiac activation patterns to facilitate treatment
Using the reconstructed activation patterns to display mapped cardiac activations to facilitate targeted treatment such as ablation or other therapy to suppress or eliminate the rhythm disorder.
The independent claims cover a novel method and system implementing paired cardiac signal derivative comparison to identify activation onsets, refining onset assignment through various averaging and weighting methods, optionally using composite signals and noise filtering, and iteratively reconstructing cardiac activation patterns to locate sources of rhythm disorders and facilitate therapeutic interventions.
Stated Advantages
Enables reconstruction of cardiac activation information in complex rhythm disorders previously not possible, allowing identification of causes or sources of such disorders.
Provides a rapid method that can be performed while sensing devices are used in or near the patient, facilitating immediate treatment following reconstruction.
Reduces complexity and number of steps compared to prior art, improving the ability to assign activation onset times amid complex and continuous activation patterns.
Improves accuracy in distinguishing local activations from far-field signals and noise by comparing derivatives across multiple sensor signals.
Documented Applications
Diagnosis and treatment of complex heart rhythm disorders such as atrial fibrillation, ventricular fibrillation, and polymorphic ventricular tachycardia.
Mapping and targeting of cardiac regions responsible for heart rhythm disorders to facilitate ablation or alternative therapies like gene therapy, stem cell therapy, pacing stimulation, or drug therapy.
Implementation with catheters comprising multiple sensors inserted into heart chambers to record electrogram signals for cardiac activation reconstruction.
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