Adjustable AV Delay Mechanism for Ventricular Tachyarrhythmia Detection
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Solution Overview
Problem
Implantable medical devices face challenges in accurately diagnosing and treating ventricular tachyarrhythmias due to under-sensing caused by atrial pacing, which inhibits detection of intrinsic ventricular contractions when the heart rate falls within a tachyarrhythmia rate zone.
Innovation Solution
The implementation of an adjustable atrioventricular (AV) delay mechanism that automatically decreases the AV delay to prevent under-sensing by ensuring the atrial pace occurs outside the tachyarrhythmia rate zone, while preserving the ventricular pace pulse interval, and disabling this feature when the LRL interval approaches the LTR zone to maintain therapeutic settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If atrial pacing is used to maintain heart rhythm, then cardiac output is improved, but under-sensing of ventricular tachyarrhythmias occurs
Solution Approach 1:
The patent applies dynamics by making the AV delay adjustable rather than fixed. The device dynamically modifies the AV delay based on detected heart rate zones, switching between a first AV delay for normal rates and a second AV delay for tachyarrhythmia zones. This dynamic adjustment allows the system to maintain effective cardiac output while preventing under-sensing of ventricular tachyarrhythmias.
Solution Approach 2:
The patent changes the parameter of AV delay based on operational conditions. When the heart rate falls within a tachyarrhythmia rate zone, the system changes the AV delay parameter from the first value to the second value, ensuring that atrial pacing does not interfere with ventricular sensing capability and allowing accurate detection of tachyarrhythmias.
2Measurement precision
If AV delay is decreased to prevent under-sensing, then detection accuracy is improved, but ventricular pace pulse interval is affected
Solution Approach 1:
The patent segments the operational ranges into distinct zones: a normal heart rate zone using a first AV delay and a tachyarrhythmia zone using a second AV delay. This segmentation allows the system to apply different AV delay values appropriate to each zone, maintaining detection accuracy when needed while preserving normal pacing intervals during normal operation.
Solution Approach 2:
The system dynamically switches between different AV delay values based on the detected heart rate zone. When transitioning from normal to tachyarrhythmia conditions, the AV delay is adjusted to prevent under-sensing, while the ventricular pace pulse interval remains preserved through coordinated adjustment of timing parameters.
3Adaptability or versatility
If multiple tachyarrhythmia rate thresholds are used to classify different tachyarrhythmias, then diagnostic capability is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by assigning different AV delay values to different operational zones (normal vs. tachyarrhythmia). This localized adjustment of parameters based on specific operational conditions allows the system to handle different tachyarrhythmia types appropriately without requiring overly complex control mechanisms for each scenario.
Data Source
AI summary
An apparatus comprises an electrical stimulation circuit, a ventricular sensing circuit, a ventricular sensing timer, and an atrial pacing timer. The ventricular sensing circuit detects an intrinsic ventricular tachyarrhythmia depolarization. The ventricular sensing timer initiates timing of a lowest tachy rate (LTR) zone interval and also a ventricular pace interval that is calculated using a lower rate limit (LRL). The atrial pacing timer calculates an atrial pace interval to follow the intrinsic ventricular depolarization using the ventricular pace interval less a paced atrioventricular (AV) delay interval, delays generation of the atrial pace until after expiration of the LTR zone interval by decreasing the paced AV delay interval when the calculated atrial pace interval is within the LTR zone interval, and disables decreasing of the paced AV delay interval when the LRL interval less the paced AV delay interval at the LRL is less than the LTR zone interval.