Cardiac Rhythm Management System Rate Modulation via Temperature Slope
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Solution Overview
Problem
Conventional pacemakers face challenges in accurately adjusting heart pacing rates in response to exercise, as they often rely on fixed or magnitude-based responses to temperature dips, which can lead to inappropriate rate changes due to poor peripheral circulation or diurnal variations, increasing complexity and power consumption.
Innovation Solution
A cardiac rhythm management system that utilizes a temperature sensor to analyze blood temperature signals, employing a high-pass filter to diminish responses over time and only considering positive temperature slopes to determine rate adjustments, thereby reducing complexity and improving accuracy in exercise response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional pacemakers use fixed or magnitude-based responses to temperature dips, then the device complexity is reduced, but the accuracy of rate adjustment is worsened due to inappropriate rate changes from poor peripheral circulation or diurnal variations
Solution Approach 1:
The patent changes the parameter from magnitude-based response to slope-based response. Instead of reacting to the absolute temperature drop magnitude, the system reacts to the rate of temperature change (slope). This parameter transformation eliminates spurious responses to diurnal variations and poor peripheral circulation while maintaining appropriate exercise response, improving accuracy without requiring complex algorithms.
Solution Approach 2:
The patent replaces complex algorithmic processing with a simpler mathematical operation (differentiation to find slope). Instead of using complex algorithms to distinguish exercise from other causes of temperature changes, the system uses the slope of temperature change as a direct indicator of exercise intensity, simplifying the processing while improving accuracy.
2Adaptability or versatility
If conventional pacemakers consider diurnal temperature variations, then the adaptability to different conditions is improved, but the device complexity and power consumption increase
Solution Approach 1:
The patent extracts and eliminates the diurnal temperature variation factor from the rate adjustment algorithm. By using slope-based response, the system automatically filters out diurnal variations and other non-exercise temperature changes, focusing only on exercise-induced temperature changes. This extraction simplifies the calculation while maintaining adaptability to exercise conditions.
Solution Approach 2:
The patent converts the potentially harmful effect of diurnal temperature variations into a benefit by using slope-based detection. The same temperature changes that could cause spurious responses (diurnal variations, poor circulation) are now automatically ignored because they lack the characteristic slope pattern of exercise, while exercise-induced temperature changes are correctly identified.
3Measurement precision
If conventional pacemakers use temperature-based activity sensors, then the measurement of exercise is improved, but the response time is worsened due to the time required for temperature changes to manifest
Solution Approach 1:
The patent performs preliminary action by continuously monitoring the slope of temperature change rather than waiting for temperature to reach a threshold. The system is always ready to detect exercise onset by monitoring the rate of change, enabling faster response compared to waiting for temperature to manifest fully.
Solution Approach 2:
The patent introduces dynamics by using the slope (rate of change) of temperature rather than static temperature values. This dynamic approach allows the system to detect exercise onset earlier and respond more quickly, as the slope changes immediately at exercise onset rather than requiring temperature to reach a predetermined level.
4Adaptability or versatility
If pacemakers increase the number of processing calculations for temperature analysis, then the adaptability to different exercise levels is improved, but the power consumption increases
Solution Approach 1:
The patent changes the computational approach from complex multi-parameter analysis to a single slope-based parameter. By using only the slope of temperature change, the system achieves exercise level differentiation with minimal calculations, significantly reducing power consumption while maintaining adaptability to different exercise intensities.
Solution Approach 2:
The patent applies partial action by using only the essential feature (slope) needed to distinguish exercise from non-exercise conditions, rather than analyzing all possible temperature parameters. This partial analysis is sufficient for the intended purpose and dramatically reduces computational load and power consumption.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides a more appropriate and proportional increase in pacing rate during exercise, reducing unnecessary rate changes and improving pacemaker longevity by eliminating the need for complex diurnal temperature variations calculations.
Implementation Method 1
A temperature sensor can detect changes in a patient's blood temperature, which varies with exercise
Implementation Method 2
employing a high-pass filter to diminish responses over time
Data Source
AI summary
A cardiac rhythm management system provides an increase in pacing rate as a combination of responses to three characteristics of a relative-temperature signal: a dip, a positive slope, and a positive magnitude. The relative-temperature signal is the difference between a short-term and a long-term temperature average. A dip produces a limited and temporary rate increase having a first proportionality. A positive slope produces a rate increase with a second proportionality. A positive magnitude produces a rate increase with a third proportionality. The dip response seeds the slope response to provide a seamless and immediate rate transition after a dip. The cardiac rhythm management system limits and filters the sum of the rate increases to provide a sensor indicated rate, which is used to stimulate the heart.