Impedance Transformation Model for Catheter Location Estimation
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Solution Overview
Problem
Existing medical device positioning systems face challenges in accurately locating electrodes in three-dimensional space within a patient's body due to instability in impedance measurements and failure to account for errors and patient movement, limiting the precision and reliability of catheter and electrode positioning.
Innovation Solution
A system that predicts impedance values using a three-dimensional impedance potential field model, integrating both impedance and magnetic sensor data to refine electrode location estimation, employing a composite model that includes a catheter model, magnetic model, and impedance model, with an extended Kalman filter for updating and improving the accuracy of electrode positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If electrical impedance-based positioning system is used to locate multiple electrodes simultaneously, then the ability to position numerous electrodes is improved, but measurement accuracy deteriorates due to electrical interference and impedance drift
Solution Approach 1:
The patent introduces magnetic sensors as an intermediary measurement mechanism. Instead of relying solely on electrical impedance measurements which are prone to drift and interference, the system uses magnetic field measurements from magnetic sensors co-located with electrodes to determine electrode positions. This intermediary approach provides a stable reference frame independent of patient anatomy and electrical interference, thereby maintaining measurement precision while enabling positioning of multiple electrodes.
2Measurement precision
If magnetic field-based positioning system is used to improve coordinate system stability, then measurement accuracy is improved, but the number of sensors that can be tracked deteriorates
Solution Approach 1:
The patent merges electrical impedance-based positioning capabilities with magnetic field-based positioning capabilities into a unified hybrid system. The system combines the strengths of both approaches: magnetic sensors provide stable coordinate system references for accuracy, while electrical impedance electrodes enable tracking of multiple points. By integrating these two subsystems, the patent achieves both high measurement precision and the ability to track numerous sensors simultaneously.
3Measurement precision
If coordinate system transformation is applied to register electrode locations to magnetic system, then positioning accuracy is improved, but reliability deteriorates due to failure to account for impedance shifts and drifts
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously monitors both magnetic sensor measurements and electrical impedance measurements. The magnetic measurements provide a stable reference frame, while the impedance measurements serve as feedback to detect and compensate for drifts and shifts. By comparing the two measurement types and using the stable magnetic reference to correct impedance-based position estimates, the system maintains both accuracy and reliability over time.
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 enhances the accuracy and stability of electrode location estimation by continuously integrating impedance and magnetic measurements, accounting for errors and patient movement, thereby improving the precision of catheter and electrode positioning in three-dimensional space.
Implementation Method 1
The system can determine P&O by applying a current across pairs of electrodes, measuring respective voltages induced at the device electrodes
Implementation Method 2
The generators provide a controlled low-strength AC magnetic field in the area of interest (i.e., an anatomical region). The detection coils produce a respective signal indicative of one or more characteristics of the sensed field
Data Source
AI summary
Systems and methods are described herein for use in predicting impedance values or responses in a three-dimensional space. Broadly, an impedance potential field and its measurement characteristics is modeled in an impedance model such that an impedance measurement may be estimated for any location within the impedance potential field. The impedance model may evolve over time based on actual impedance measurements of electrodes located in the three-dimensional space. Initially a plurality of patch electrodes to provide an impedance field to a three-dimensional space while electrodes disposed in the impedance field measure impedances. While each patch is driven, a number of independent impedance fields exist between the non-driven patches. These independent impedance potential fields may be estimated and mapped to impedance measurements of the electrode(s) at locations(s) within the impedance field to model the impedance field.