Pacemaker Respiration Synchronization via Non-Linear Oscillator
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Solution Overview
Problem
Cardiac pacemaker devices struggle to effectively synchronize heart rhythms with respiratory cycles, leading to inefficient energy use and potential cardiovascular risks due to the loss of respiratory sinus arrhythmia (RSA), which is a natural phenomenon that stabilizes blood gases and reduces heartbeats.
Innovation Solution
A cardiac pacemaker system that determines the timing of electrical stimulus signals based on respiration signals, using a neuronal oscillator to modulate the timing of these signals according to a non-linear function, ensuring synchronization between heart rhythms and respiratory cycles, thereby maintaining an integer ratio or multiple of stimulus signal periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a cardiac pacemaker device uses fixed timing for electrical stimulus signals, then the device complexity is low, but the synchronization with respiratory cycles is lost and energy efficiency deteriorates
Solution Approach 1:
The pacemaker employs a non-linear oscillator that dynamically adjusts the timing of electrical stimulus signals based on respiratory cycle detection. The oscillator continuously adapts its output frequency and phase to match the subject's respiratory pattern, transforming the fixed timing system into a dynamic one that responds to physiological changes in real-time
Solution Approach 2:
The system incorporates a feedback mechanism where the non-linear oscillator receives input from respiratory cycle detection and adjusts the stimulus signal timing accordingly. This closed-loop control ensures that the pacemaker maintains synchronization with the subject's natural respiratory sinus arrhythmia, optimizing energy efficiency while preserving cardiac function
2Reliability
If the pacemaker synchronizes stimulus signals with respiratory cycles, then cardiovascular health is improved, but the timing control complexity increases
Solution Approach 1:
The non-linear oscillator serves as an intermediary component that bridges the respiratory cycle detection and the electrical stimulus signal generation. It processes the respiratory input and transforms it into appropriately timed pacing signals, simplifying the overall control architecture while achieving reliable synchronization with respiratory sinus arrhythmia
Solution Approach 2:
The system changes the timing parameters of the electrical stimulus signals dynamically based on respiratory phase detection. During inspiration, the pacemaker adjusts the inter-stimulus interval to match the natural acceleration of heart rate, and during expiration, it adjusts for the deceleration, thereby maintaining cardiovascular stability through parameter adaptation
3Use of energy by moving object
If the pacemaker uses natural respiratory sinus arrhythmia patterns, then energy efficiency is improved, but the ability to maintain fixed heart rate control is reduced
Solution Approach 1:
The non-linear oscillator enables the pacemaker to dynamically switch between fixed heart rate mode and respiratory-synchronized mode. The system can adapt its behavior based on clinical requirements, providing energy-efficient RSA-synchronized pacing when appropriate while maintaining the ability to deliver fixed-rate pacing when stable heart rate control is prioritized
Solution Approach 2:
The pacemaker implements periodic modulation of stimulus signals that mirrors the natural periodicity of respiratory sinus arrhythmia. By detecting the respiratory cycle period and applying corresponding periodic variations to the pacing interval, the system achieves energy efficiency through physiological synchronization while retaining control flexibility
Data Source
AI summary
The disclosure relates to determining timing of electrical stimulus signals temporally modulated by a respiration signal. Aspects of the disclosure relate to an apparatus comprising: a first input stage configured to receive a first input signal indicative of respiration; a respiration analysis module configured to determine, from the first input signal, a signal indicative of instantaneous respiration duty cycle; and a synchronization module configured to generate the timing of the stimulus signals as a function of the signal indicative of respiration duty cycle in order to maintain a bias towards synchronization between the respiration period and an integer ratio of the periods between stimulus signals.