Atherectomy Burr Torque Estimation for Excess Load Protection
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Solution Overview
Problem
Existing atherectomy devices struggle to effectively excise occlusive material from blood vessels without damaging the surrounding vessel wall or previously implanted stents, particularly when encountering hard occlusive materials like calcified deposits, and lack effective torque control mechanisms to prevent device failure or patient injury.
Innovation Solution
An atherectomy system with a drive mechanism and controller that regulates operation based on estimated load torque, using equations to calculate and manage angular velocity, acceleration, and friction to prevent excessive torque, featuring a Proportional Integral Derivative (PID) controller for precise torque management and rapid burr actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the atherectomy burr rotates at high speed to effectively excise hard occlusive material, then the productivity increases, but the torque may exceed safe limits causing device failure or patient injury
Solution Approach 1:
The controller continuously monitors motor current and calculates estimated load torque in real-time, comparing it against a predetermined torque threshold. When the torque exceeds the threshold, the controller immediately stops or reverses the drive mechanism, preventing device failure or patient injury while allowing high-speed operation during normal conditions
Solution Approach 2:
The system dynamically adjusts the rotational speed and direction of the atherectomy burr based on real-time torque conditions. The controller can increase speed for efficient excision when torque is within limits, and rapidly stop or reverse when excessive torque is detected, optimizing both productivity and safety
2Productivity
If the drive mechanism applies high torque to remove calcified deposits, then the productivity increases, but the harmful effects on vessel wall increase
Solution Approach 1:
The controller uses motor current feedback to calculate estimated load torque and compares it against a predetermined torque threshold. When torque exceeds the threshold, indicating potential vessel wall damage risk, the controller immediately stops or reverses the drive mechanism, preventing harmful effects while maintaining high productivity during safe operation
Solution Approach 2:
The system establishes a predetermined torque threshold before operation that represents the safe limit for vessel wall interaction. This threshold acts as a safety cushion, allowing the system to operate at high torque levels for efficient deposit removal while automatically preventing exceedance of safe limits that could cause vessel damage
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 system effectively excises occlusive material while minimizing damage to vessels and stents, ensuring safe operation by stopping or reversing the drive mechanism when excessive torque is detected, thus protecting the device and patient.
Implementation Method 1
A controller is adapted to regulate operation of the drive mechanism and to calculate an estimated load torque at the atherectomy burr based upon at least one of an angular velocity of the atherectomy system and an angular acceleration of the atherectomy system
Implementation Method 2
The drive mechanism may include a drive cable that is coupled with the atherectomy burr and a drive motor that is adapted to rotate the drive cable
Data Source
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AI summary
An atherectomy system includes a drive mechanism adapted to rotatably actuate an atherectomy burr and a controller that is adapted to regulate operation of the drive mechanism. The controller is adapted to calculate an estimated load torque at the atherectomy burr based upon at least one of an angular velocity of the atherectomy system and an angular acceleration of the atherectomy system. The controller is further adapted to stop or reverse the drive mechanism when the estimated load torque at the atherectomy burr exceeds a torque threshold.