Atherectomy Burr Controller Mode Switching
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Solution Overview
Problem
Existing atherectomy devices face challenges in efficiently removing occlusive material from body lumens without damaging surrounding vessel walls or previously implanted stents, particularly when encountering stuck cutting elements.
Innovation Solution
The atherectomy system includes an atherectomy burr and a drive mechanism actuated by a controller that switches between operating modes. In the first mode, the burr operates at a speed reference with a torque limit. When the burr becomes stuck, the controller switches to a second mode, where it uses a position reference, alternates rotational directions, and temporarily exceeds the torque limit to facilitate burr movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the atherectomy burr operates at a speed reference with a predetermined torque limit, then the device can safely remove occlusive material without damaging surrounding tissues, but the burr becomes stuck when encountering resistant occlusions
Solution Approach 1:
The system dynamically switches between two operating modes: a first mode with speed reference and predetermined torque limit for safe operation, and a second mode with position reference and increased torque limit for freeing stuck burrs. This dynamic adaptation allows the system to respond to different operational conditions, maintaining safety during normal operation while enabling effective recovery when the burr becomes stuck
Solution Approach 2:
The controller changes operational parameters by switching from speed reference to position reference, and temporarily increases the torque limit from the predetermined value to a higher value. This parameter change enables the system to overcome stuck conditions while returning to safe operating parameters when the burr is freed
2Productivity
If the controller temporarily exceeds the predetermined torque limit in second operating mode, then the stuck burr can be freed, but there is risk of damaging surrounding vessel walls or stents
Solution Approach 1:
The system employs periodic alternating rotational directions (forward and reverse) when operating in the second mode with increased torque limit. This periodic action distributes the high torque application over time and in both directions, preventing continuous high-stress contact with surrounding tissues while working to free the stuck burr
Solution Approach 2:
The system dynamically switches between two operating modes: a first mode with speed reference and predetermined torque limit for safe operation, and a second mode with position reference and increased torque limit for freeing stuck burrs. This dynamic adaptation allows the system to respond to different operational conditions, maintaining safety during normal operation while enabling effective recovery when the burr becomes stuck
3Ease of operation
If the controller uses position reference and alternates rotational directions, then the burr can be freed from stuck position, but the control system complexity increases
Solution Approach 1:
The controller is designed to perform multiple functions: it operates in a first mode with speed reference for normal operation, switches to a second mode with position reference when the burr is stuck, and executes alternating rotational directions. This multi-functionality is achieved through a single unified control system that adapts its operation based on detected conditions, managing complexity through integrated design
Data Source
AI summary
An atherectomy system includes a drive mechanism adapted to rotatably actuate an atherectomy burr and a controller that is adapted to operate the drive mechanism in a first operating mode in which the atherectomy burr is operated at a speed reference and with a predetermined torque limit. The controller is adapted to determine when the atherectomy burr becomes stuck while in the first operating mode and is further adapted to, when the atherectomy burr becomes stuck, operate the drive mechanism in a second operating mode that is different from the first operating mode.