Vagus Nerve Stimulation Device with Dynamic Activity Calibration
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Solution Overview
Problem
Existing VNS therapies for heart failure patients are not effectively adaptable to varying levels of activity, as they rely on fixed thresholds, which can hinder exercise tolerance by preventing heart rate acceleration during physical effort.
Innovation Solution
A medical device with a tracking module that automatically calibrates VNS stimulation based on patient activity levels, using a classifier to determine dynamic activity classes and select appropriate therapy configurations, allowing for regular recalibration to monitor long-term changes in patient condition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If VNS therapy is applied to reduce heart rate and myocardial contractility, then cardiac remodeling is reduced, but exercise tolerance is worsened due to prevented heart rate acceleration during physical effort
Solution Approach 1:
The patent applies dynamics by making the VNS therapy parameters adaptive rather than fixed. The system continuously monitors activity level and automatically adjusts stimulation parameters in real-time, transitioning between different therapy configurations based on whether the patient is at rest or exercising, thus resolving the contradiction between cardiac remodeling reduction and exercise tolerance
Solution Approach 2:
The patent changes the parameters of VNS therapy based on activity level. Different stimulation parameters are applied depending on whether the patient is performing physical activity or not, allowing the system to optimize both cardiac remodeling prevention during rest and exercise tolerance during activity by adjusting parameters dynamically
2Device complexity
If fixed thresholds are used for VNS therapy modulation, then device complexity is reduced, but adaptability to varying patient activity levels and disease evolution is worsened
Solution Approach 1:
The system performs self-calibration by automatically determining activity level thresholds based on historical data from the same patient. The processor analyzes past activity patterns and disease evolution to adapt thresholds dynamically, eliminating the need for manual programming while maintaining high adaptability to individual patient characteristics
Solution Approach 2:
The patent implements feedback mechanisms where the system continuously monitors activity level and compares it against calibrated thresholds, automatically adjusting therapy parameters. This closed-loop control enables the system to adapt to varying patient conditions over time while maintaining manageable complexity through automated decision-making
Data Source
AI summary
An active implantable medical device includes a VNS pulse bursts generator for stimulation of the vagus nerve according to several selectable configurations. The device may further include a sensor of the current activity level of the patient. The generator is controlled on the activity signal via a classifier determining the class of the current level of activity among a plurality of classes of activity. A controller selects a configuration of VNS therapy depending on the class of activity thus determined. Limits of the activity classes are dynamically changeable by a calibration module that conducts a historical analysis of the successive current activity levels over a predetermined analysis period. The calibration module can prepare a histogram of the historical analysis, and can define the limits of the activity classes depending on the outcome of the historical analysis and the histogram.