Nonlinear Electric Field Location System for Catheter Mapping
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Solution Overview
Problem
Current catheter-based location-tracking systems for electro-anatomical mapping assume linear dependence of electric fields on intrabody locations, leading to inaccuracies and the need for cumbersome calibration methods.
Innovation Solution
A method and system that derive and solve nonlinear equations between electrical signal-values and coordinates using a calibration phase with a mapping-electrode and location-measuring sensor, followed by application in an investigation phase to accurately determine locations within the body, employing cubic relations and magnetic calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If linear dependence assumption is used for electric fields, then calculation simplicity is improved, but location accuracy deteriorates
Solution Approach 1:
The patent changes the mathematical model from linear to nonlinear (cubic) relationships between electric field measurements and catheter position. This parameter change in the functional relationship allows the system to capture the true nonlinear behavior of electric fields in biological tissues, thereby improving location accuracy while maintaining computational feasibility through efficient cubic equation solving algorithms.
2Measurement precision
If nonlinear equations are used to model electric fields, then location accuracy is improved, but calculation complexity increases
Solution Approach 1:
The patent employs cubic (third-order polynomial) equations to model the nonlinear relationship between electric field measurements and catheter position. These curved mathematical relationships better represent the actual nonlinear behavior of electric fields in heterogeneous biological tissues compared to linear models, achieving superior location accuracy while maintaining manageable computational complexity through established numerical solution methods.
3Measurement precision
If calibration is performed at multiple positions, then mapping accuracy is improved, but calibration time increases
Solution Approach 1:
The patent performs calibration at multiple predetermined positions within the heart chamber before the actual mapping procedure. This preliminary calibration establishes the nonlinear relationship parameters between electric field measurements and positions, which are then reused during the investigation phase. This approach ensures high mapping accuracy while minimizing calibration time by performing the time-consuming multi-position calibration only once beforehand.
4Measurement precision
If cubic interpolation is used on a fine grid, then tracking precision is improved, but computational load increases
Solution Approach 1:
The patent extracts and utilizes only the essential nonlinear relationship information from calibration data, represented by cubic equation parameters. Rather than performing computationally intensive cubic interpolation on fine grids during real-time tracking, the system uses the pre-determined cubic relationships to directly calculate catheter position from electric field measurements, significantly reducing computational load while maintaining high tracking precision.
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 more accurate and less cumbersome location tracking, simplifying catheterization procedures and improving the precision of electro-anatomical mapping by accounting for the nonlinear variation of electric fields within the body.
Implementation Method 1
a sensor of a location-measuring system... intrabody locations were measured using a catheter-based magnetic location-tracking system
Implementation Method 2
active electrode sites that are activated to impose an electric field within the chamber. The blood volume and wall motion modulate the electric field, which is detected by passive electrode sites on the preferred catheter
Data Source
Figure 1
Figure 2~3
AI summary
A method includes, in a calibration phase, positioning a calibration-tool, including a mapping-electrode and a sensor of a location-measuring system, in an organ. The calibration-tool is tracked at different positions in the organ using the location-measuring system. A set of calibration data points is generated at the respective different positions, each calibration data point including signal-values obtained using the mapping-electrode and a corresponding position measurement of the sensor by the location-measuring system. The method further includes, in an investigation phase that is subsequent to the calibration phase, positioning an investigation-tool at a location in the organ. The signal-values at the location are measured using a mapping-electrode of the investigation-tool. Using a subset of the calibration data points, coordinates of the location are determined by deriving a respective nonlinear relation between the signal-values obtained using the mapping-electrode of the investigation-tool, and the coordinates of the location and solving the nonlinear relation.