Catheter Force Estimation via Proximal Dithering
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Solution Overview
Problem
Current minimally invasive procedures face challenges in accurately measuring forces experienced by medical instruments, such as catheters, at the distal end during contact with tissue structures due to the compliant nature of these instruments and associated frictional loads, making it difficult for physicians to gauge the forces applied or sensed at the proximal end.
Innovation Solution
A method involving a dithering device connected to the proximal portion of the working catheter, which dithers relative to the guide catheter, allowing for force measurement at the proximal region and estimation of the force at the distal end by comparing force waveforms during contact and non-contact states, providing real-time feedback to the physician.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If force measurement is performed at the proximal end of the catheter, then the measurement location is accessible, but the measurement precision deteriorates due to frictional loads and compliant instrument nature
Solution Approach 1:
The patent applies dithering (mechanical vibration) to the catheter at high frequency (e.g., 50-100 Hz) to create dynamic motion that allows differentiation between frictional forces and tissue contact forces. By analyzing the force waveform during dithering cycles, the system can identify the point where tissue contact occurs, thereby measuring distal end forces with high precision despite proximal measurement location
Solution Approach 2:
The patent implements a feedback mechanism where force sensors continuously monitor proximal end forces during dithering, and the system processes this data to estimate distal end forces in real-time. The feedback loop allows the system to compensate for frictional effects and provide accurate force estimation at the distal end based on proximal measurements
2Measurement precision
If dithering motion is applied to measure force, then measurement precision improves, but device complexity increases due to additional dithering mechanism
Solution Approach 1:
The dithering mechanism serves multiple functions: it enables force measurement, provides friction compensation, and facilitates real-time distal end force estimation. By making the dithering device multi-functional, the patent justifies the added complexity through significant improvements in measurement capability and procedural safety
Solution Approach 2:
The dithering mechanism acts as an intermediary that translates difficult-to-measure distal end forces into measurable proximal end force variations. By introducing this intermediate element, the system can indirectly measure distal forces with high precision without requiring direct sensing at the distal tip
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 enables accurate and timely estimation of forces at the distal end of the catheter, enhancing the precision of minimally invasive procedures by providing real-time feedback and reducing errors associated with frictional forces, thus improving the execution of diagnostic and therapeutic interventions.
Implementation Method 1
The working catheter and guide catheter are dithered with respect to one another using a dithering device operatively connected to a proximal portion of the working catheter
Implementation Method 2
The force experienced by the working catheter at a proximal region is measured through at least one dithering cycle
Data Source
AI summary
A method for estimating the force on a distal end of a working catheter includes positioning a portion of a robotically controlled guide catheter and working catheter into a body lumen wherein a distal end of the working catheter projects distally from a distal end of the guide catheter. The working catheter and guide catheter are dithered with respect to one another using a dithering device operatively connected to a proximal portion of the working catheter. The coupling may occur directly to the working catheter or via a seal such as a Touhy seal. The force experienced by the working catheter at a proximal region is measured through at least one dithering cycle. The force at the distal end of the working catheter is then estimated based on the measured force at the proximal region. The estimated force may be displayed to a physician on, for example, a monitor.