Cardiac Pacing Stability Check for Capture Loss Detection
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Solution Overview
Problem
Miniaturized implantable medical devices, such as leadless pacemakers, face challenges in reducing battery drain while maintaining capture of the heart's rhythm, as conventional safety margins increase current consumption and risk loss of capture.
Innovation Solution
A stability check mechanism is implemented to determine the heart's rhythm stability before performing capture management operations, allowing for a reduced safety margin by adjusting pacing pulse amplitude during the check and ignoring refractory ventricular sensed events to assess ventricular intervals, thereby reducing energy expenditure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a higher safety margin is used in capture management, then the reliability of capture is improved, but the battery drain increases and device longevity decreases
Solution Approach 1:
The patent implements dynamic adjustment of the safety margin based on real-time assessment of capture status. The device transitions from a static, fixed safety margin to a dynamic parameter that varies with patient condition, allowing the safety margin to be increased when capture is unreliable and decreased when capture is stable, thereby optimizing both reliability and battery life.
Solution Approach 2:
The patent changes the parameter of safety margin from a fixed value to a variable parameter that is continuously adjusted based on captured cardiac signals and rhythm analysis. This allows the device to adapt the safety margin to current physiological conditions, reducing unnecessary energy consumption while maintaining adequate capture reliability.
2Reliability
If capture management operations are performed frequently, then the reliability of capture is improved, but the energy consumption increases
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors captured cardiac signals and rhythm characteristics to determine when capture management operations are necessary. The system uses this feedback to intelligently trigger threshold tests and safety margin adjustments only when needed, rather than performing them on fixed schedules, thereby reducing unnecessary energy consumption.
Solution Approach 2:
The patent replaces continuous or fixed-schedule capture management operations with periodic actions triggered by specific events or conditions. The device performs threshold tests and safety margin checks periodically based on detected rhythm changes, patient conditions, or intervals since last testing, rather than continuously or at fixed times, reducing overall energy consumption.
3Duration of action of stationary object
If the safety margin is reduced to save energy, then the battery life is improved, but the risk of loss of capture increases
Solution Approach 1:
The patent performs preliminary threshold testing and capture status assessment before reducing the safety margin. The device first determines the patient's current capture status and rhythm stability, then selectively reduces the safety margin only when preliminary assessments indicate stable capture, thereby extending battery life while maintaining safety.
Solution Approach 2:
The patent implements dynamic adjustment of the safety margin based on real-time assessment of capture status. The device transitions from a static, fixed safety margin to a dynamic parameter that varies with patient condition, allowing the safety margin to be increased when capture is unreliable and decreased when capture is stable, thereby optimizing both reliability and battery life.
Data Source
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AI summary
Techniques for determining stability of a patient's intrinsic rhythm in a cardiac pacing device. Cardiac pacing pulses are delivered to a heart chamber of a patient by the device at a first pulse amplitude. The device measures a first series of intervals between successive sensed and paced events. The device then determines whether the first measured series of intervals meets a stability criterion. Responsive to the first measured series of intervals failing to meet the stability criterion, the device determines whether the first measured series of intervals includes an interval between a delivered pacing pulse and a sensed event that is less than a defined duration. Responsive to the interval between a delivered pacing pulse and a sensed event being less than the defined duration, the device delivers cardiac pacing pulses at a second pulse amplitude and determines whether the second measured series of intervals meets the stability criterion.