Vena Cava Filter Retrieval Using Snare Sheath
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Solution Overview
Problem
Conventional vena cava filters with tulip or conical shapes are difficult to retrieve from the femoral side due to their design, which requires a second percutaneous entry for removal, as the legs splay outwardly and have hooks or barbs to hold them in position, limiting retrieval options.
Innovation Solution
A medical device retrieval apparatus featuring a sheath with coaxially arranged first and second sheath portions and a carrier element, equipped with a snare that can be exposed to capture and retract the filter from the same direction it was deployed, allowing for retrieval without altering the filter's design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tulip or conical shaped filter is deployed in the vena cava, then filtration effectiveness and positional stability are improved, but retrieval difficulty increases requiring a second percutaneous entry
Solution Approach 1:
The filter is nested within a retrieval sheath that can be introduced through the same femoral access point. The sheath contains a carrier element with a snare that can engage the filter's retrieval feature, allowing the entire assembly to be withdrawn through the original access site without requiring a second percutaneous entry.
Solution Approach 2:
A retrieval sheath and carrier element act as intermediary devices between the operator and the implanted filter. These intermediaries enable engagement with the filter's retrieval feature and facilitate withdrawal through the same access point, resolving the contradiction between reliable implantation and easy retrieval.
2Reliability
If the filter legs splay outwardly with hooks or barbs for secure positioning, then retention in the vessel is improved, but retrieval from the deployment side becomes impossible
Solution Approach 1:
The filter is designed with segmented functionality: the legs with hooks or barbs provide secure anchoring in the vessel wall, while a separate retrieval feature (such as a tab or loop) extends into the filter body. This segmentation allows the retrieval mechanism to engage the central feature without disturbing the anchored legs, enabling withdrawal from the deployment side.
Solution Approach 2:
Instead of requiring retrieval from the opposite side (jugular) where the filter legs would naturally point, the design enables retrieval from the same side (femoral) by providing a retrieval feature that can be engaged by a snare mechanism introduced through the original access point.
3Adaptability or versatility
If a modified filter design is used to enable retrieval from the deployment side, then retrieval versatility is improved, but device complexity increases
Solution Approach 1:
The filter design incorporates a multi-functional retrieval feature that serves dual purposes: it facilitates secure engagement by the snare mechanism during retrieval while maintaining the filter's normal filtration function during implantation. This universal feature enables retrieval from the deployment side without requiring extensive structural modifications.
Data Source
AI summary
A medical device retrieval apparatus includes a sheath provided with first and second sheath portions arranged coaxially and movable relative to one another between a snaring position and a closed position. A carrier element is disposed in the sheath and is movable at least relative to the first sheath portion. A snare is attached to the carrier. The snare is locatable within the first sheath portion. The first sheath portion includes a chamber in which a medical device is receivable. In the snaring position the snare is locatable between the first sheath portion and a deployment handle. A method of retrieving a medical device is also provided.