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A real-time ST-segment monitoring algorithm for implantable devices
R W Stadler1, S N Lu, S D Nelson
1Medtronic, Inc, Cardiac Rhythm Management, Minneapolis, MN 55432, USA. robert.stadler@medtronic.com
Journal of Electrocardiology
|January 10, 2002
Summary
A new algorithm enables continuous ST-segment monitoring in implantable devices, aiding arrhythmia and chest pain diagnosis. This efficient algorithm achieves high sensitivity and positive predictivity for ischemia detection.
Area of Science:
- Biomedical Engineering
- Cardiology
- Signal Processing
Background:
- Continuous ST-segment monitoring via implantable devices offers potential for arrhythmia substrate clarification, diagnosis of nonspecific chest pain, and optimized anti-ischemic therapy.
- Existing ST-segment monitoring algorithms for surface electrocardiograms require computational demands that are too high for implantable devices, necessitating minimization for device longevity.
Purpose of the Study:
- To develop and validate a computationally efficient algorithm for ST-segment monitoring suitable for current implantable cardiac devices.
- To assess the algorithm's performance in detecting ischemic episodes and its suitability for long-term continuous monitoring.
Main Methods:
- An algorithm was developed that identifies a fiducial point (FPT) on the QRS complex, measures ST-segment deviation relative to the isoelectric level, and quantifies features like R-R interval and R-wave amplitude.
- Noise and ectopic beats are rejected by analyzing feature inconsistencies against adaptive normal ranges. ST-segment deviation over time is filtered to exclude non-ischemic changes.
- Performance was evaluated using the European Society of Cardiology ST-T Database (180 hours, 250 ischemic episodes).
Main Results:
- The algorithm achieved a sensitivity of 79% [74% 84%] and a positive predictivity of 81% [76% 86%] for detecting ischemic episodes.
- Performance was statistically equivalent to existing surface electrocardiogram algorithms validated on the same dataset.
- Estimated computational burden allows for continuous processing of two electrogram channels for over 5 years using current implantable device technology.
Conclusions:
- A novel ST-segment monitoring algorithm has been developed that is implementable in current implantable devices.
- The algorithm demonstrates sensitivity and positive predictivity comparable to state-of-the-art methods.
- This technology holds promise for improved diagnosis and management of cardiac conditions through continuous monitoring.