Atherectomy Motor Stall Control for Patient Torque Reduction

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Solution Overview

Problem

Current medical devices for atherectomy procedures face challenges in safely and effectively managing stall conditions, which can lead to increased torque and force on patients, potentially causing harm during plaque removal in vascular treatments.

Innovation Solution

An atherectomy system with a control unit that monitors motor states, such as torque and speed, and adjusts the motor state by reversing torque direction, reducing voltage, or changing current to decelerate the motor when a stall condition is detected, utilizing sensors for real-time data and a reference schedule to manage motor states and mitigate forces during jams or obstructions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the motor continues to operate at high torque during a stall condition, then the atherectomy device can maintain cutting force, but the torque and force on the patient increases potentially causing harm

Engineering Contradiction:
Improvecutting forceVSAvoidtorque on patient
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The control unit continuously monitors motor parameters (current, speed, torque) and uses this feedback to detect stall conditions. When a stall is detected through abnormal parameter patterns, the control unit automatically reduces motor torque to prevent harm to the patient while maintaining device functionality.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The motor torque is made dynamically adjustable based on real-time operating conditions. The control unit can rapidly change torque levels from high (for cutting) to low (for safety during stall) in response to detected conditions, allowing the system to adapt its mechanical output to prevent harm while maintaining cutting capability when needed.

Inventive Principle:
Principle #15Dynamics

2Object-affected harmful factors

If the control unit reduces motor torque during stall conditions, then patient safety is improved, but the cutting capability of the device is reduced

Engineering Contradiction:
Improvetorque on patientVSAvoidcutting capability
Core Design Contradiction:
Object-affected harmful factorsVSProductivity

Solution Approach 1:

The system uses continuous feedback monitoring of motor parameters to distinguish between temporary stalls during normal cutting operations and abnormal stalls requiring torque reduction. The control unit analyzes patterns in current, speed, and torque to make intelligent decisions about when to reduce torque, preserving cutting capability during normal operation while protecting the patient during true stall conditions.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The control unit changes motor operating parameters (torque, current, speed) based on detected conditions. By adjusting these parameters dynamically rather than maintaining fixed high torque, the system optimizes the balance between cutting performance and patient safety, reducing torque only when necessary while maintaining full cutting capability during normal operation.

Inventive Principle:
Principle #35Parameter changes

3Object-affected harmful factors

If the control unit continuously monitors motor parameters to detect stall conditions, then patient safety is improved, but the device complexity increases

Engineering Contradiction:
Improvetorque on patientVSAvoidcontrol system complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The control unit implements feedback monitoring of motor parameters (current, speed, torque) to detect stall conditions. This automated monitoring system provides continuous safety oversight without requiring additional mechanical safety devices, managing complexity through electronic control rather than mechanical redundancy.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces potential mechanical safety mechanisms with an electronic control system that monitors motor parameters and automatically adjusts torque. This substitution of electronic control for mechanical safety devices reduces overall device complexity while maintaining or improving safety effectiveness.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP3723634B1Rotational medical device
Publication Date: 2024.02.28 BOSTON SCIENTIFIC SCIMED INC
  • EP3723634B1 patent drawingFigure 1
  • EP3723634B1 patent drawingFigure 2
  • EP3723634B1 patent drawingFigure 3

AI summary

Medical systems and methods for making and using medical systems are disclosed. Example medical systems may include an atherectomy system configured to engage and remove plaque from walls in vessels of a vascular system. The atherectomy system may include a drive shaft, a rotational member coupled to an end of the drive shaft, a motor coupled to the drive shaft to rotate the rotational member, and a control unit configured to control a motor state of the motor. The motor may be an electric motor. The control unit may adjust the motor state to decelerate the motor in response to detecting a jam or a stall condition. The jam or stall condition may be detected when a speed of the motor or other motor state reaches or goes beyond a threshold value as prescribed by a reference schedule.