Microcatheter Sensor Mounting to Minimize Induced Strain
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Solution Overview
Problem
Conventional pressure sensors on microcatheters used for calculating Fractional Flow Reserve (FFR) are prone to distortion due to bending stresses, leading to incorrect pressure readings, and require the use of specialized FFR guidewires, which clinicians prefer not to use for interventional procedures.
Innovation Solution
A catheter design with a deformable member or intermediate member with a hinge between the pressure sensor and the catheter shaft, or a pressure sensor suspended above the shaft wall, reduces stress and strain on the sensor, allowing its use with conventional guidewires and minimizing catheter profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure sensor is mounted on the distal end of a microcatheter, then pressure measurements can be obtained for FFR calculation, but the sensor is subjected to bending stresses that cause distortion and incorrect readings
Solution Approach 1:
A deformable member is introduced as an intermediary element between the pressure sensor and the catheter shaft. This deformable member absorbs and isolates bending stresses, preventing them from being transmitted to the pressure sensor while still allowing the sensor to accurately measure pressure at the distal end of the catheter.
2Measurement precision
If a specialized FFR guidewire is used to accommodate the pressure sensor, then accurate measurements can be obtained, but clinicians cannot use conventional guidewires for interventional procedures
Solution Approach 1:
The catheter design integrates a pressure sensor with a deformable member that isolates it from bending stresses, enabling the same catheter to function both as a measurement device for FFR calculation and as a guide wire for interventional procedures. This universal design allows clinicians to use conventional guidewires while still obtaining accurate pressure measurements.
3Measurement precision
If the pressure sensor is made small and highly sensitive, then measurement capability is improved, but the sensor becomes more susceptible to distortion from stress
Solution Approach 1:
The deformable member serves as a protective intermediary that shields the small, highly sensitive pressure sensor from bending stresses. By placing this stress-absorbing element between the sensor and the rigid catheter shaft, the sensor can maintain its small size and high sensitivity without being vulnerable to distortion from external forces.
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 design ensures accurate pressure measurements by minimizing distortion of the pressure sensor, enabling the use of conventional guidewires and reducing bending stresses, thus improving the reliability of FFR calculations.
Implementation Method 1
The deformable member reduces the amount of stress and strain transferred to the pressure sensor, thereby reducing distortion of the sensor
Data Source
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AI summary
A catheter, such as a fractional flow reserve catheter, includes an elongate shaft having a proximal end optionally coupled to a handle or luer fitting and a distal end having a distal opening. A pressure sensing wire extends to the distal portion of the elongate shaft to be coupled to a pressure sensor mounted on the distal end for measuring a pressure of a fluid within lumen of vessel. The pressure sensor wire is disposed within a pocket formed adjacent to the pressure sensor thereby minimizing the profile of the catheter. Bending or flexing stress or strain experienced by a pressure sensor mounted to a fractional flow reserve catheter when tracking the catheter through the vasculature creates a distortion of the sensor resulting in an incorrect pressure reading or bend error. In order to isolate the sensor from bending or flexing stress and strain, the sensor is mounted so that the sensor is spaced apart from the elongate shaft of the catheter.