Vena Cava Filter Retrieval Device with Expandable Interlocking Mechanism
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Solution Overview
Problem
Vena cava filters become difficult or impossible to remove due to endothelialization and off-centering, which prevents engagement with traditional retrieval hooks.
Innovation Solution
A device with a distal hub and proximal hub, featuring a flexible, radially expandable interlocking arrangement and a stylet wire, allows for the radial expansion to engage and remove the filter without needing to engage the retrieval hook, using a catheter to position and retract the filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional retrieval hook is used to remove the filter, then the removal process is simple, but the filter cannot be removed when it is endothelialized or off-centered
Solution Approach 1:
The retrieval device is divided into multiple functional components: a delivery catheter, an expandable interlocking arrangement with multiple elements, and a pull wire system. This segmentation allows the device to navigate complex anatomical conditions and engage the filter through multiple contact points rather than relying on a single hook engagement
Solution Approach 2:
The interlocking arrangement transitions from a compressed low-profile state during delivery to an expanded three-dimensional configuration at the target site. This dimensional change enables the device to engage the filter from multiple angles and provide circumferential contact, overcoming the limitations of traditional single-point hook engagement
2Duration of action of stationary object
If the filter is left in place for long-term filtration, then thrombosis protection is maintained, but the filter becomes endothelialized and difficult to remove
Solution Approach 1:
The expandable interlocking arrangement is designed to engage the filter struts before significant endothelialization occurs. The device includes features such as barbs or hooks that can penetrate the filter structure and establish secure attachment prior to tissue overgrowth, enabling future removal even after extended periods of filter retention
Solution Approach 2:
The interlocking arrangement changes its physical parameters from a compressed delivery configuration to an expanded working configuration. This parameter change allows the device to transition from navigating the vasculature to engaging and securing the filter, providing the necessary mechanical advantage for removal against endothelialized tissue
3Adaptability or versatility
If the filter becomes off-centered or tilted, then deployment flexibility is improved, but retrieval hook engagement becomes impossible
Solution Approach 1:
The interlocking arrangement is designed with dynamic elements that can adapt to various filter orientations and positions. The expandable structure includes flexible components that can conform to off-centered or tilted filter configurations, maintaining engagement capability regardless of the filter's final deployment orientation
Solution Approach 2:
The retrieval device is designed with universal engagement features that can interact with the filter structure in multiple ways. The interlocking arrangement can engage the filter through various mechanisms depending on the filter's position and orientation, making the retrieval process independent of the filter's deployment alignment
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
Enables the safe and effective removal of vena cava filters, even when they are tilted or endothelialized, by providing sufficient traction and positive fixation to withdraw the filter from the body vessel.
Implementation Method 1
a flexible, radially expandable interlocking arrangement extending from the distal hub to the proximal hub
Implementation Method 2
The positioning device and the stylet wire may be configured to perform a longitudinal relative movement between proximal hub and the distal hub
Data Source
AI summary
An apparatus for retrieving an implanted device from a body vessel includes a distal hub with an elongated, bendable distal tip and with a first marker visible through body tissue with at least one imaging method; a proximal hub with a central longitudinal channel therethrough, arranged proximal from the distal hub, and bearing a second marker. A stylet wire extends from the distal hub through the central longitudinal channel of the proximal hub to a proximal stylet wire end. A flexible, radially expandable interlocking arrangement extends from the distal hub to the proximal hub. An elongated positioning device extending proximally from the proximal hub to a proximal device end. The positioning device and the stylet wire may be configured to perform a longitudinal relative movement between proximal hub and the distal hub, and the interlocking arrangement expands radially when the proximal and distal hubs approach each other.