Adaptive Endocardial Acceleration Signal Averaging
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Solution Overview
Problem
Existing techniques for processing endocardial acceleration signals in active implantable medical devices face a compromise between precision and speed of response, leading to noise contamination and reduced representation of heart mechanics, especially due to cycle-to-cycle variability and the risk of introducing atypical cycles in averaging processes.
Innovation Solution
A device with dynamic adaptation capabilities that modifies processing parameters and validation criteria based on detected changes in patient state or events, such as heart rate instability or apnea, to optimize the averaging of endocardial acceleration signals, ensuring accurate and timely representation of heart mechanics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the EA signal is averaged over a large number of cycles to improve precision, then measurement precision is improved, but the speed of response deteriorates due to the increased time constant
Solution Approach 1:
The patent applies dynamics by making the number of cycles N used for averaging variable rather than fixed. The processing means dynamically adapt N based on detected patient state or events, increasing N when precision is prioritized and decreasing N when rapid response is needed, thus resolving the contradiction between measurement precision and speed of response
Solution Approach 2:
The patent changes the parameter N (number of cycles for averaging) from a constant to a variable parameter that can be modified in response to detected changes in patient state. This allows the system to optimize the trade-off between precision and response speed by adjusting N according to clinical needs
2Speed
If the averaging is calculated over a low number of cycles to improve speed of response, then speed of response is improved, but measurement precision deteriorates due to noise contamination
Solution Approach 1:
The system dynamically adjusts the number of cycles N used for averaging based on the detected patient state. When rapid response is needed, N is reduced to improve speed of response, while when precision is prioritized, N is increased to reduce noise contamination through more extensive averaging
Solution Approach 2:
The parameter N is modified from a fixed low value to a variable parameter that can be increased when precision is needed and decreased when speed is needed, allowing the system to adapt to different clinical situations and resolve the contradiction between speed and precision
3Measurement precision
If validation criteria are made rigorous to improve precision, then measurement precision is improved, but the quantity of processed cycles deteriorates due to rejection of atypical cycles
Solution Approach 1:
The validation criteria are made dynamic rather than fixed, allowing the system to adjust the strictness of cycle acceptance based on detected patient state. When precision is prioritized, more rigorous criteria are applied, and when maintaining adequate cycle quantity is needed, criteria are relaxed to include more cycles in the averaging process
Solution Approach 2:
The validation thresholds and criteria parameters are modified based on detected events or patient state, allowing the system to balance between precision (stricter criteria) and quantity of retained cycles (more lenient criteria) according to clinical needs
Data Source
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AI summary
The device includes means for continuously acquiring an endocardial acceleration (EA) signal, with: segmentation into EA sub-signals, each over the duration of a cardiac cycle; separation of the EA1 and EA2 components; intercorrelation between the EA sub-signals of each component and temporal registration with respect to a reference cycle; application of a series of validation criteria; and averaging to deliver an overall average EA signal over one cycle. It also includes detection means (24) capable of detecting a change in the patient's state or the occurrence of a predetermined event in the patient, and means (26, 28) for dynamically adapting the treatment means, capable of modifying, upon detection of this change in state or predetermined event, at least one of the aforementioned validation criteria and/or at least one of the parameters of the treatment means.