System and method for reconstructing cardiac activation information
Inventors
Narayan, Sanjiv • Briggs, Carey Robert • Sehra, Ruchir
Assignees
US Department of Veterans Affairs • Topera Inc • University of California San Diego UCSD
Publication Number
US-9668666-B2
Publication Date
2017-06-06
Expiration Date
2031-08-24
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Abstract
In a system and method for reconstructing cardiac activation information, an analysis cardiac signal and a reference cardiac signal are accessed and processed to determine a first point of change in the analysis cardiac signal at which a derivative of the analysis cardiac signal diverges with respect to a derivative of the reference cardiac signal. The signals are processed to determine a second point of change in the analysis cardiac signal at which a different derivative of the analysis cardiac signal with respect to a different derivative of the reference cardiac signal. 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 (AF), ventricular tachycardia (VT), and ventricular fibrillation (VF). It operates by accessing an analysis cardiac signal and a reference cardiac signal from a patient and processing them to detect points of change where derivatives of the analysis signal diverge with respect to derivatives of the reference signal. Activation onset times are then assigned based on a mathematical association of these points of change to define cardiac activation indicating beats in the analysis signal.
The background identifies that heart rhythm disorders are common and serious, with complex disorders being difficult to treat due to a lack of accurate tools to locate the causes. Existing systems perform poorly in complex disorders because activation onset patterns vary from beat to beat, making it hard to identify activation onsets and distinguish local activations from far-field or noise signals. There are no known methods capable of reconstructing cardiac activation information amid complex signals, especially for complex rhythm disorders.
The invention solves this problem by providing a method that compares derivatives of cardiac signals at successive time points to find significant points of change that correspond to activation onsets. It selects and processes pairs of analysis and reference signals from arrays of sensors within the heart, determines points of change above thresholds, and mathematically associates these points to assign activation onset times. The system can iterate through multiple signals, reconstruct activation patterns, and thereby identify sources of rhythm disorders to enable targeted and immediate treatment such as ablation.
Claims Coverage
The patent includes several independent claims covering a method for reconstructing cardiac activation information, a system configured to perform this reconstruction, and a method of treating cardiac rhythm disorders using the reconstruction.
Determining points of change in analysis signal relative to reference signal derivatives
The method involves processing an analysis cardiac signal and a reference cardiac signal to determine a first point of change where a derivative (zero, first, or second order) of the analysis signal diverges from the corresponding derivative of the reference signal, and a second point of change where a different order derivative of the analysis signal diverges from the corresponding derivative of the reference signal.
Assigning activation onset time based on mathematical association of points of change
An activation onset time is assigned in the analysis cardiac signal at a point derived from a mathematical association of the first point of change and the second point of change. This association can be an average (representing a majority or plurality of reference signals), selection based on highest difference relative to thresholds, or based on the highest order derivative above a threshold.
Utilizing composite cardiac signals and ratio-based significance values
Composite cardiac signals formed by combining analysis and reference signals (e.g., by subtraction) are used to compute ratio values at points, representing differences between derivatives of reference, analysis, and composite signals. Largest ratio values determine significant points of change serving as activation onsets.
Iterative processing of multiple cardiac signals and pairs for activation reconstruction
The method and system iteratively select pairs of signals from multiple acquired cardiac signals, perform processing to determine multiple activation onsets indicating beats, and reconstruct cardiac activation patterns from assigned activation onset times, enabling identification of rhythm disorder sources.
Method of treating cardiac rhythm disorder using reconstructed activation pattern
The method further includes reconstructing activation patterns based on assigned activation onset times to identify sources of the cardiac rhythm disorder and treating cardiac tissue at the source to suppress or eliminate the disorder.
The independent claims cover a comprehensive system and method that utilizes comparative derivative analysis of paired cardiac signals to identify activation onsets. They include iterative signal pairing for reconstruction of activation patterns and applications to treatment of cardiac rhythm disorders.
Stated Advantages
Ability to reconstruct cardiac activation information in complex rhythm disorders where activation patterns change from beat to beat, which was not previously possible.
Rapid determination of the cause or source of heart rhythm disorders, facilitating immediate and targeted treatment such as ablation.
Reduction in complexity and number of steps compared to prior methods, improving efficiency and accuracy in reconstructing activation onset times.
Capability to process signals while a sensing device is used in or near the patient, enabling real-time or near real-time treatment decisions.
Documented Applications
Diagnosis and treatment of complex heart rhythm disorders such as atrial fibrillation, ventricular tachycardia, ventricular fibrillation, atrial tachycardia, supraventricular tachycardia, atrial flutter, supraventricular ectopic beats, and premature ventricular complexes.
Use with catheters having arrays of sensors inserted into the heart via blood vessels to detect cardiac activation signals.
Processing signals from electrodes spatially arranged in the heart chambers (e.g., right atrium, left atrium, right ventricle, left ventricle) to reconstruct activation patterns.
Treatment of identified sources of cardiac rhythm disorders via energy delivery methods including ablation with radiofrequency, cryoenergy, microwave, ultrasound, gene therapy, stem cell therapy, pacing stimulation, or drug therapy.
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