Cardiac Event Detection Using Baseline ECG Comparison
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Solution Overview
Problem
Current systems for detecting cardiac events, such as acute myocardial infarction and ischemia, are inadequate due to unreliable detection algorithms, lack of sophisticated programmability, and insufficient data storage capabilities in implanted devices, leading to potential false positives and negatives, and insufficient capability to differentiate between exercise-induced ischemia and acute myocardial infarction.
Innovation Solution
A guardian system comprising a cardiosaver device implanted with subcutaneous electrodes that uses advanced detection algorithms to identify cardiac events by comparing electrogram data with baseline data, adjusting thresholds for sensitivity, and storing both normal and abnormal electrogram segments for accurate detection and alerting patients through internal and external alarms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard 12 lead ECG detection is used, then cardiac events can be detected, but detection reliability is poor without knowing patient's normal ECG pattern
Solution Approach 1:
The system performs preliminary action by establishing a baseline ECG pattern from the patient's normal heart activity before attempting to detect cardiac events. This baseline is stored and used for comparison during event detection, enabling reliable identification of deviations from normal patterns without requiring prior knowledge of the patient's normal ECG by the operator.
Solution Approach 2:
The system implements feedback by continuously comparing real-time ECG signals against the stored baseline pattern and automatically adjusting detection thresholds based on the comparison results. This feedback mechanism improves both measurement precision and reliability by adapting to the patient's specific cardiac characteristics.
2Difficulty of detecting and measuring
If subcutaneous electrodes are used for ST segment shift detection, then detection capability is provided, but ideal electrode placement has not been explored
Solution Approach 1:
The system applies self-service by using the implanted device itself to determine optimal electrode placement. The device automatically identifies suitable subcutaneous locations for electrodes based on signal quality metrics, eliminating the need for external expertise in electrode positioning while maintaining detection capability.
3Reliability
If Fischell et al detection system is used, then acute myocardial infarction detection is provided, but false positive and false negative detection probability is not reduced
Solution Approach 1:
The system implements dynamics by making detection thresholds adaptive rather than fixed. Thresholds are dynamically adjusted based on the patient's baseline ECG pattern, heart rate variability, and activity level, which reduces false positives during exercise while maintaining sensitivity for true cardiac events.
Solution Approach 2:
The system applies parameter changes by modifying multiple detection parameters simultaneously including threshold levels, time windows for analysis, and comparison criteria against baseline. These parameter adjustments are made based on the specific characteristics of each patient's ECG, improving measurement precision while maintaining reliability.
4Volume of stationary object
If limited system memory is used, then device size is reduced, but electrogram and other data storage capability is insufficient
Solution Approach 1:
The system extracts and stores only the most critical data elements: baseline ECG patterns, detected event segments, and essential metadata. Non-essential data is excluded or summarized, allowing adequate storage capacity within limited memory while maintaining device size constraints.
Solution Approach 2:
The system implements discarding and recovering by overwriting old baseline data with new baselines as they become available, and by storing only representative event segments rather than continuous recordings. This approach maximizes data retention within limited storage while preserving the ability to recover and analyze critical cardiac information.
Data Source
AI summary
A system for the detection of cardiac events occurring in a human patient is provided. At least two electrodes are included in the system for obtaining an electrical signal from a patient's heart. An electrical signal processor is electrically coupled to the electrodes for processing the electrical signal and a patient alarm means is further provided and electrically coupled to the electrical signal processor. The electrical signal is acquired in the form of electrogram segments, which are categorized according to heart rate, ST segment shift and type heart rhythm (normal or abnormal). Baseline electrogram segments are tracked over time.