Atherectomy Drive Shaft Stall Control for Safe Unwinding

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Solution Overview

Problem

Existing rotational atherectomy devices face issues with uncontrolled release of angular momentum during stall conditions, leading to potential damage to the drive shaft and vasculature due to uncontrolled unwinding and 'ringing', which can cause trauma.

Innovation Solution

Implementing a control mechanism that detects a stall condition using sensors and applies controlled dynamic braking or reverse torque to safely release stored rotational energy and angular momentum, preventing damage by managing the unwinding process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the motor continues to apply torque during a stall condition, then the atherectomy tool can overcome the blockage, but angular momentum builds up causing uncontrolled unwinding and potential damage

Engineering Contradiction:

Improveability to overcome blockageVSAvoiduncontrolled unwinding damage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The system continuously monitors motor current and rotational speed to detect stall conditions. When a stall is detected, the controller automatically transitions from applying forward torque to applying reverse torque, creating a closed-loop feedback system that prevents harmful uncontrolled unwinding while maintaining the ability to overcome blockages during normal operation

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system applies reverse torque as a preliminary counter-action immediately upon detecting a stall condition. This reverse torque prevents the build-up of excessive angular momentum before uncontrolled unwinding can occur, thereby preventing damage to the drive shaft and vasculature before the harmful effect manifests

Inventive Principle:

Principle #9Preliminary anti-action

2Object-affected harmful factors

If the motor stops immediately upon detecting a stall, then angular momentum build-up is prevented, but the atherectomy tool cannot overcome the blockage

Engineering Contradiction:

Improveangular momentum build-upVSAvoidability to overcome blockage

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The system uses periodic monitoring of motor current and rotational speed to detect stall conditions. Rather than continuous intervention, the system periodically checks operational parameters and only intervenes when a stall condition is detected, allowing normal operation to proceed uninterrupted while preventing harmful effects when needed

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system dynamically adjusts the motor torque based on real-time detection of stall conditions. During normal operation, the motor applies forward torque to overcome blockages. Upon detecting a stall, the system dynamically transitions to applying reverse torque, creating a dynamic response that adapts to changing operational conditions rather than using a fixed control strategy

Inventive Principle:

Principle #15Dynamics

3Loss of energy

If the drive shaft is allowed to unwind freely after a stall, then stored energy is released, but uncontrolled movement causes trauma to the vasculature

Engineering Contradiction:

Improvestored rotational energy releaseVSAvoidvasculature trauma

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The system converts the potentially harmful uncontrolled unwinding motion into a beneficial controlled process. By applying reverse torque during the unwinding phase, the system dissipates stored rotational energy in a controlled manner, transforming what would be a harmful uncontrolled release into a safe, monitored energy dissipation process that prevents vasculature trauma

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 solution provides a controlled and predictable unwinding of the stalled drive shaft, minimizing damage to the drive shaft and vasculature by effectively managing and dissipating stored energy, thereby ensuring safe operation during atherectomy procedures.

Implementation Method 1

the motor driver outputs are configured to tie the motor windings together to begin dynamic braking

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

the controller is configured to instruct the motor driver to begin applying a reverse torque to the proximal end of the drive shaft

Methodology Applied

Scientific EffectTorque: Torque

Data Source

PatentUS20250339170A1Management of stored angular momentum in stalled intravascular rotational drive shafts for atherectomy

Publication Date: 2025.11.06 CARDIOVASCULAR SYSTEMS INC

AI summary

A control system for releasing stored rotational energy and angular momentum in a drive shaft with a distally positioned atherectomy tool, wherein the atherectomy tool is stuck within vasculature. The control system is configured to manage the release of the stored energy and angular momentum of the drive shaft safely and predictably.