Contractility Correction via Impedance and Non-HF Factors
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Solution Overview
Problem
Current methods for estimating contractility in heart failure diagnostics are hindered by the influence of non-heart failure factors, making it difficult to obtain a true and independent assessment of cardiac performance.
Innovation Solution
The use of cardiogenic impedance (CI) measurements in conjunction with additional data such as Z0 values, heart rate, respiration, activity level, and posture to derive surrogate signals for cardiac volumes, pressures, and oxygen requirements, allowing for the normalization and removal of non-heart failure effects from contractility estimates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contractility is estimated using CI measurements, then cardiac performance assessment is obtained, but non-HF factors (preload, afterload, metabolic state, heart rate, neurohormonal influences) contaminate the measurement
Solution Approach 1:
The patent segments the contractility estimation process into multiple independent measurement components: CI measurements for contractility, Z0 measurements for preload, blood pressure measurements for afterload, and metabolic measurements. Each component is measured and corrected separately, allowing the final contractility estimate to have non-HF factors removed through systematic correction of each segment.
Solution Approach 2:
The patent introduces intermediary correction factors that mediate between the raw CI measurements and the final corrected contractility estimate. These correction factors, derived from independent measurements of preload, afterload, and metabolic state, act as intermediaries to remove the confounding influence of non-HF factors from the contractility assessment.
2Measurement precision
If multiple surrogate signals are collected to correct for non-HF factors, then contractility measurement accuracy is improved, but system complexity increases
Solution Approach 1:
The patent makes the implantable device universal by enabling it to perform multiple functions: CI measurements for contractility, Z0 measurements for preload, blood pressure monitoring for afterload, and metabolic state assessment. This multi-functionality consolidates what would otherwise require multiple separate devices into a single universal platform, managing complexity through integration rather than proliferation of separate systems.
Solution Approach 2:
The patent merges multiple measurement functions (CI, Z0, blood pressure, metabolic measurements) into a single integrated system. By combining these previously separate measurement capabilities into one device, the patent reduces the overall system complexity that would arise from coordinating multiple independent devices while maintaining the precision benefits of comprehensive multi-parameter monitoring.
Data Source
AI summary
A method for trending heart failure measures cardiogenic impedance (CI) and obtains signals representing estimates for or direct measurements of at least one of cardiac volume and pressure of the heart when the CI measurements were obtained. The method identifies correction factors based on the signals and applies the correction factors to the contractility estimates. A system for trending heart failure includes a contractility module to determine contractility estimates from CI measurements taken along at least a first vector through a heart, and a collection module to receive signals representing estimates for or direct measurements of at least one of cardiac volume and pressure of the heart when the CI measurements were obtained. The system further includes a factor module to identify correction factors based on the signals and a correction module to apply the correction factors to the contractility estimates.