Implantable Heart Sound Sensor Posture Correction
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Solution Overview
Problem
Heart sound amplitude measurements in implantable medical devices are confounded by patient posture, leading to variations that can mask changes indicative of disease progression, such as congestive heart failure, due to changes in sensor coupling and hemodynamic tissue stiffness.
Innovation Solution
An implantable system comprising a heart sound sensor, a posture sensor, and a controller circuit that measures heart sounds in correspondence with patient posture, using algorithms to apply scaling factors and filter out noise, allowing for accurate trending of heart sounds independent of posture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If heart sound measurements are taken without considering patient posture, then the monitoring system is simple and easy to operate, but the measurement precision deteriorates due to posture-dependent variations in heart sound amplitude
Solution Approach 1:
The patent introduces posture sensors as an intermediary component that detects patient posture and provides this information to the controller. The controller then uses posture information to select appropriate scaling factors that compensate for posture-dependent variations in heart sound amplitude. This intermediary posture detection mechanism enables precise heart sound measurements across different postures without requiring complex real-time adjustments to the heart sound sensor itself.
Solution Approach 2:
The patent applies parameter changes by introducing scaling factors that are selected based on detected patient posture. These scaling factors adjust the heart sound amplitude measurements to compensate for posture-dependent variations. The system changes the measurement parameter (amplitude) dynamically based on the posture parameter, enabling consistent disease progression detection regardless of patient position.
2Measurement precision
If posture-dependent scaling factors are applied to correct heart sound measurements, then measurement precision improves, but device complexity increases due to additional sensors and processing algorithms
Solution Approach 1:
The patent implements preliminary action by pre-calculating and storing multiple scaling factors corresponding to different patient postures (e.g., supine, seated, standing). Instead of performing complex real-time calculations when posture changes occur, the system has already prepared the appropriate correction factors in advance. The controller simply needs to detect the current posture and retrieve the corresponding pre-computed scaling factor, significantly reducing processing complexity while maintaining measurement precision.
3Reliability
If heart sound monitoring is performed across multiple postures with correction algorithms, then reliability of disease progression detection improves, but ease of operation deteriorates due to more complex measurement protocols
Solution Approach 1:
The patent implements self-service by enabling the monitoring system to automatically detect patient posture using integrated posture sensors and autonomously apply the appropriate scaling factors to correct heart sound measurements. The system performs these corrections without requiring patient awareness or manual intervention. Patients simply need to wear the device, and the system handles posture detection and measurement correction automatically, maintaining ease of operation while improving reliability.
Data Source
AI summary
A system to monitor heart sounds. The system comprises an implantable heart sound sensor operable to produce an electrical signal representative of at least one heart sound, a heart sound sensor interface circuit coupled to the heart sound sensor to produce a heart sound signal, an implantable posture sensor operable to produce an electrical signal representative of a patient's posture, and a controller circuit, coupled to the heart sound sensor interface circuit and the posture circuit. The controller circuit is operable to measure at least one heart sound in correspondence with at least one sensed patient posture.