Removable Vena Cava Filter with Dynamic Anchoring Hooks

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Solution Overview

Problem

Conventional vena cava filters are not easily removable due to endotheliosis and often become off-centered or tilted, leading to permanent implantation, and there is a need for a design that minimizes scratching or scraping during delivery and retrieval.

Innovation Solution

A removable vena cava filter with primary and secondary struts that expand to capture thrombi, featuring anchoring hooks and a retrieval hook, designed to deploy and collapse for effective thrombi capture and safe removal, using superelastic materials to maintain non-traumatic engagement with the vessel wall.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional filters are deployed in the vena cava, then thrombi can be captured effectively, but the filter becomes difficult to remove due to endotheliosis and fibrous reaction

Engineering Contradiction:

Improvethrombi capture effectivenessVSAvoidfilter removability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The filter is designed with dynamic characteristics allowing it to transition between expanded and collapsed states. The struts are configured to be flexible enough to collapse for removal while maintaining structural integrity when expanded for filtration, enabling the filter to be removed before endotheliosis occurs

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The filter incorporates a retrieval hook that engages with the delivery catheter before deployment. This preliminary engagement allows the filter to be retrieved by simply pulling the catheter, eliminating the need for complex retrieval procedures and ensuring removal can be performed before tissue ingrowth occurs

Inventive Principle:

Principle #10Preliminary action

2Reliability

If conventional filters are deployed, then thrombi filtering function is achieved, but the filter becomes off-centered or tilted leading to permanent implantation

Engineering Contradiction:

Improvefiltering functionVSAvoidfilter positioning stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The filter employs asymmetric strut design where the first strut has a different configuration than the second strut. This asymmetry allows the filter to self-center within the vena cava by creating unequal forces that naturally align the filter with the vessel axis, preventing off-centering and tilting

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The struts are designed with curved configurations rather than straight lines. The curved struts follow the natural contour of the vena cava and provide radial support that maintains the filter in a centered, non-tilted position, ensuring stable positioning and preventing permanent implantation

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Ease of operation

If filters are delivered through introducer systems, then percutaneous placement is achieved, but scratching or scraping of anchoring hooks occurs during delivery and retrieval

Engineering Contradiction:

Improvepercutaneous delivery capabilityVSAvoidmechanical trauma to hooks

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The filter incorporates a flexible membrane that covers the anchoring hooks during delivery. This thin film protects the sharp hooks from scratching or scraping against the introducer catheter walls while allowing the filter to be delivered percutaneously through the vein

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The anchoring hooks are designed to be dynamic, capable of rotating or flexing during delivery to navigate the introducer catheter without causing mechanical trauma. Once deployed, the hooks assume their anchoring position to secure the filter while minimizing damage to surrounding tissues

Inventive Principle:

Principle #15Dynamics

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 filter effectively captures thrombi while minimizing endotheliosis and allowing for safe retrieval, reducing the risk of permanent implantation and trauma during delivery and removal.

Implementation Method 1

using superelastic materials to maintain non-traumatic engagement with the vessel wall

Methodology Applied

Scientific EffectSuperelasticity: Pseudoelasticity

Data Source

PatentUS8246651B2Removable vena cava filter for reduced trauma in collapsed configuration

Publication Date: 2012.08.21 COOK MEDICAL TECHNOLOGIES LLC

AI summary

The present invention provides a method of capturing thrombi in a blood vessel, which includes delivering a removable filter in a collapsed state within the blood vessel and deploying the filter to an expanded state within the blood vessel. The filter includes a plurality of primary struts and a plurality of secondary struts emanating from a hub and extending arcuately along a longitudinal axis and linearly radially. Each primary strut has an arcuate segment including first and second curved portions. Each secondary strut includes first and second arcs. The primary struts terminate with an anchoring hook. Each primary strut crosses another primary strut along the longitudinal axis in the collapsed state such that the arcuate segments occupy a first diameter and the anchoring hooks occupy a second diameter, the first diameter being greater than the second diameter for filter retrieval or delivery. In the expanded state, the secondary struts centralize the filter in the blood vessel and the anchoring hooks engage with the blood vessel.