Thrombus Removal Expansion Mechanism With Force-Limiting Outer Tube
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Solution Overview
Problem
Existing medical devices for removing thrombi in a living body lumen can apply excessive expansive force to the expansion portion, potentially damaging body tissues such as blood vessel walls due to direct connection of the distal and proximal arms with a spring, leading to deformation and tissue damage.
Innovation Solution
A medical device with a rotatable elongated shaft, an expansion portion, and a connection mechanism that includes a distal and proximal contact portion, a first and second restricting portion, and an elastic member to control the expansion force, preventing excessive force application on the expansion portion by ensuring the distal contact portion is positioned proximal to the first restricting portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the proximal end of the distal arm and the proximal end of the proximal arm are directly connected with a spring, then the expansion portion can be expanded in the radial direction, but excessive expansive force may occur causing body tissue damage or expansion portion deformation
Solution Approach 1:
A contact portion is introduced as an intermediary element between the spring (acting member) and the expansion portion. The contact portion includes a distal contact portion and a proximal contact portion that interact with restricting portions to mediate the force transmission. This intermediary mechanism ensures that the spring force is controlled and does not directly translate to excessive expansive force on the expansion portion, thereby preventing tissue damage while maintaining expandability.
Solution Approach 2:
The patent changes the parameter of force control by positioning the distal contact portion proximal to the first restricting portion when the spring pushes the proximal contact portion. This positional parameter change creates a mechanical constraint that limits the maximum expansive force. Additionally, the restricting portions are designed with specific geometries (protrusions and recesses) that control the axial movement range, thereby regulating the radial expansion force applied to the expansion portion.
2Adaptability or versatility
If the distal contact portion is positioned to allow full axial movement, then the expansion portion can expand freely, but the distal contact portion may press the first restricting portion causing excessive force
Solution Approach 1:
The patent controls the axial movement parameter of the outer tube by positioning the distal contact portion proximal to the first restricting portion during the expansion phase. This positional constraint changes the movement parameter from 'unrestricted' to 'controlled range'. The restricting portions are designed with specific axial positions that define the permissible movement range, ensuring that the distal contact portion cannot press against the first restricting portion under normal operation, thereby maintaining adaptability while preventing excessive force.
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 device effectively breaks up thrombi without excessive force, preventing damage to body tissues and the expansion portion by controlling the expansion force, ensuring safe and controlled operation within the body lumen.
Implementation Method 1
an acting member capable of applying a force that moves the outer tube in a distal direction to the outer tube by movement of the outer tube in a proximal direction
Data Source
AI summary
A medical device includes an expansion portion that rotates to break-up an object and that is prevented from receiving excessive force. The expansion portion is at a distal part of a shaft portion, a connection portion is fixed to a proximal part of the expansion portion, and an outer tube accommodates the shaft portion. The outer tube includes distal and proximal contact portions. The connection portion includes a first restricting portion distal to the distal contact portion and a second restricting portion proximal to the distal contact portion. An operation unit of the medical device includes a housing, a lever member fixed to the outer tube, and an elastic member that applies a force moving the outer tube in a distal direction to the outer tube. When the elastic member pushes the proximal contact portion in the distal direction, the distal contact portion is proximal to the first restricting portion.