Reconstructing Surface ECG from Endocardial Electrograms
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Solution Overview
Problem
Current methods for reconstructing surface electrocardiogram (ECG) signals from endocardial electrogram (EGM) signals are limited in providing a comprehensive view of cardiac activity, often resulting in biased signals due to changes in heart electrical axis and patient pathology evolution, requiring frequent recalibration and using multiple devices for patient monitoring.
Innovation Solution
A method involving a vectorial approach to estimate surface ECG by calculating an endocardial vectogram through orthogonalization and angular resealing, using a Karhunen-Loeve transform and adaptive neural networks for non-linear filtering, allowing for reconstruction of all ECG leads and accounting for patient-specific parameters like heart orientation and pathology evolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If surface electrodes are placed and ECG recorder is used to collect ECG signals, then comprehensive view of cardiac activity is obtained, but patient visit complexity and frequency of visits increase
Solution Approach 1:
The patent creates a copy of the surface ECG signal by reconstructing it from endocardial EGM signals obtained from the implanted device. The reconstruction algorithm generates synthetic ECG leads (I, II, III, aVR, aVL, aVF, V1-V6) that replicate the information normally obtained from surface electrodes, eliminating the need for separate ECG recording equipment during follow-up visits.
Solution Approach 2:
The implanted medical device is made multi-functional by enabling it to provide both its primary therapeutic function (pacing, defibrillation, or resynchronization) and the secondary function of ECG signal reconstruction. The device uses its existing endocardial electrodes and processing capabilities to generate comprehensive ECG information, making a single device serve multiple purposes.
2Measurement precision
If EGM signals are used directly for cardiac rhythm analysis, then local electrical activity information is obtained, but global cardiac activity visualization is limited
Solution Approach 1:
The patent transforms the local EGM signals into a global ECG representation by applying mathematical transformation algorithms that synthesize multiple ECG leads from the endocardial electrode data. This dimensional transformation converts localized electrical activity measurements into a comprehensive multi-lead ECG view that displays global cardiac electrical activity across different spatial orientations.
3Measurement precision
If reconstruction algorithm is calibrated during learning phase, then accuracy for specific patient condition is improved, but adaptability to pathology evolution decreases
Solution Approach 1:
The patent implements a dynamic reconstruction algorithm that can adapt its calibration parameters based on changes in the patient's cardiac condition. The system allows recalibration when pathology evolves, enabling the algorithm to maintain accuracy across different disease states. The calibration is not fixed but can be updated to reflect the patient's current cardiac anatomy and electrical propagation characteristics.
4Loss of information
If multiple devices (ECG recorder and implant programmer) are used for patient monitoring, then comprehensive data collection is achieved, but visit time and complexity increase
Solution Approach 1:
The patent merges the functions of the ECG recorder and the implant programmer into a single integrated solution. The implantable device itself performs ECG signal reconstruction using its embedded processing capabilities, eliminating the need for separate external equipment. The practitioner uses only the implant programmer to retrieve and analyze the reconstructed ECG data along with other device telemetry information, consolidating multiple monitoring functions into one workflow.
Data Source
AI summary
The reconstruction of a surface electrocardiogram based upon an endocardial electrogram. This method includes: (a) acquisition (10) of a plurality of endocardial electrogram signals (EGM) through a plurality of endocardial leads defined based upon endocardial electrodes; (b) calculation (12), by combining the endocardial electrogram (EGM) signals acquired at step (a), of the corresponding endocardial vectogram (VGM); (c) angular rescaling (14) of the orthonormalized mark of the endocardial vectogram (VGM) with that of the surface vectocardiogram (VCG); (d) estimation (16), based upon the endocardial vectogram (VGM) calculated at step (b), of a reconstructed surface vectocardiogram (VCGreconstructed), and (e) calculation (18) of the surface electrocardiogram (ECG) corresponding to said reconstructed surface vectocardiogram (VCGreconstructed).