Catheter Wire Loops for Millimeter Positioning
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Solution Overview
Problem
Existing electrophysiology catheters face challenges in accurately determining the position and orientation of multi-electrode arrays within the heart due to limitations in sensor technology, particularly in reconstructing the location of wire frames with millimeter precision.
Innovation Solution
A framework comprising several loops of electrically conducting wire forming a cage-like structure, where each loop functions as a single-axis magnetic sensor, allowing for precise determination of location and orientation by partitioning into triangles and applying constraints to optimize the reconstruction process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional electromagnetic mapping sensors (3-7 mm length) are used in multi-electrode catheters, then the sensor technology is well-established, but the position and orientation determination of wire frames cannot achieve millimeter precision
Solution Approach 1:
The patent combines multiple sensor functions into a single wire loop structure. Each wire loop serves both as a structural element of the catheter framework and as a magnetic sensor, eliminating the need for separate sensor components. This merging approach achieves millimeter-level precision while reducing the overall quantity of sensor materials required.
Solution Approach 2:
The wire loops are designed to perform multiple functions: they provide structural support for the catheter framework and simultaneously act as magnetic sensors for position and orientation determination. This multi-functionality resolves the contradiction by using the same material for both structural and sensing purposes, achieving high precision without proportionally increasing sensor quantity.
2Measurement precision
If wire loops are made large to improve sensor sensitivity, then measurement precision improves, but the loops cannot be deployed through narrow catheter lumens
Solution Approach 1:
The wire loops are designed with dynamic deployment characteristics. They are compressed into a small configuration for insertion through narrow catheter lumens, then expand to a larger configuration once deployed in the heart chamber. This dynamic size change allows the loops to achieve sufficient sensor sensitivity while remaining compatible with narrow delivery catheters.
Solution Approach 2:
The wire loops are nested within the catheter lumen in a compressed state during delivery. Upon deployment, they expand outward from the catheter, transitioning from a small nested configuration to a larger operational configuration. This nesting approach enables large loops to be delivered through small catheters.
3Measurement precision
If multiple independent sensors are used to determine framework position, then measurement accuracy improves, but the device complexity increases
Solution Approach 1:
The catheter framework is segmented into multiple wire loops, with each loop serving as an independent magnetic sensor. The position and orientation of the entire framework is determined by combining measurements from these segmented loop sensors. This segmentation approach achieves high reconstruction accuracy while maintaining relatively simple individual sensor elements.
Solution Approach 2:
The patent replaces complex mechanical positioning systems with magnetic field sensing. Instead of using mechanical encoders or complex mechanical linkages to determine position, the system uses wire loops that passively sense magnetic fields. This substitution reduces device complexity while maintaining or improving measurement 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
The solution enables accurate determination of the catheter's position and orientation to within a millimeter, enhancing the precision of electrophysiological mapping and ablation procedures.
Implementation Method 1
exposing the wire loops to magnetic fluxes at respective frequencies, reading signals from the wire loops responsively to the magnetic fluxes at the respective frequencies
Data Source
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AI summary
Catheterization of the heart is carried out using a framework formed by a plurality of electrically conducting wire loops. The wire loops are modeled as polygons, each subdivided into a plurality of triangles,. The wire loops are exposed to magnetic fluxes at respective frequencies, and signals read from the loops. Theoretical magnetic fluxes in the polygons are computed as sums of theoretical magnetic fluxes in the triangles thereof, The location and orientation of the framework in the heart is determined by relating the computed theoretical magnetic fluxes to the signals.