Cardiac Catheter Force Sensor Zeroing via Blood Pool Visualization
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Solution Overview
Problem
Current methods for verifying contact between a catheter and cardiac tissue during ablation procedures are unreliable, particularly due to impedance-based binary contact indications that are sensitive to changes in body-surface electrode impedance, and drift in force sensors used for measuring contact force, which can lead to inaccurate force readings.
Innovation Solution
A method and apparatus that utilize a contact force sensor and location sensors within a catheter to generate images of a blood pool, define exclusion zones to ensure accurate manual zeroing of the contact force sensor by navigating the catheter to a region within the blood pool, away from the endocardial surface and other catheters, using image processing to highlight suitable zeroing regions, thereby ensuring accurate force measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If impedance-based binary contact indication is used to verify catheter-tissue contact, then contact verification is simplified, but the measurement reliability deteriorates due to sensitivity to body-surface electrode impedance changes
Solution Approach 1:
The patent replaces electrical impedance-based contact detection with a mechanical force sensor (load cell) that directly measures contact force between the catheter and tissue. This substitution eliminates sensitivity to electrical impedance variations while providing direct mechanical measurement of contact, resolving the contradiction between operational simplicity and measurement reliability.
2Measurement precision
If force sensors are used to measure contact force, then contact force measurement capability is improved, but measurement precision deteriorates due to sensor drift
Solution Approach 1:
The patent implements a zeroing feature that allows the operator to establish a baseline force reading before beginning measurements. This preliminary calibration action compensates for sensor drift by resetting the reference point, thereby maintaining measurement precision and reliability throughout the procedure.
Solution Approach 2:
The system allows dynamic adjustment of the zero reference level based on procedural needs. By changing the reference parameter (zero point) during the procedure, the system compensates for drift and maintains accurate relative force measurements even as absolute sensor characteristics change over time.
3Ease of operation
If manual zeroing of contact force sensor is performed without spatial guidance, then zeroing operation is simplified, but measurement reliability deteriorates due to inaccurate zeroing location
Solution Approach 1:
The patent integrates visual feedback from electroanatomical mapping system that displays catheter position relative to the heart chamber geometry. This feedback mechanism guides the operator to appropriate locations for zeroing (e.g., known non-contact positions), ensuring that zeroing occurs at spatially accurate locations while maintaining operational simplicity through intuitive visual cues.
Solution Approach 2:
The electroanatomical mapping system serves as an intermediary that translates complex spatial relationships into visual guidance. This intermediary provides the operator with contextual information about catheter position and suitable zeroing locations, bridging the gap between simple manual operation and precise spatial awareness.
Data Source
AI summary
A probe having a contact force sensor is inserted into a cardiac chamber and an image of the blood pool is generated. A portion of the blood pool is removed from the image to retain a remaining portion of the blood pool. A determination is made that the distal segment of the probe is within the remaining portion of the blood pool, and responsively to the determination the contact force sensor is manually zeroed.