Intravascular Filter Retrieval Using Bead Engagement
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Solution Overview
Problem
Existing intravascular filters often become difficult or impossible to remove due to endotheliosis and fibrous reactions, leading to their permanent implantation in patients even after the initial medical condition has resolved.
Innovation Solution
A retriever device comprising a sheath and an elongated member with a bead or protrusion that can engage and pull the filter into the sheath for removal, allowing for easier extraction by moving the bead longitudinally to capture and retract the filter through its gaps, even in cases of significant cellular growth or embedding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a filter is implanted in a patient to prevent embolism, then the patient's safety is improved, but the filter becomes difficult or impossible to remove due to endotheliosis and fibrous reactions
Solution Approach 1:
The filter is divided into multiple struts with gaps between them. The retrieval device uses a cable with a bead that can pass through these gaps to engage and capture the filter struts, allowing selective engagement of filter segments for removal.
Solution Approach 2:
A retrieval device consisting of a cable with a bead and a sheath is introduced as an intermediary tool. The bead acts as a mediator that can pass through the filter gaps, engage the struts, and pull the filter into the sheath for removal without direct manipulation of the embedded filter.
2Ease of operation
If a filter remains implanted in a patient for life, then removal difficulty is avoided, but the device complexity and patient burden increase
Solution Approach 1:
The filter design includes features that enable self-retrieval. The struts are configured with gaps that allow a bead to pass through and engage the struts from the inside, enabling the filter to be removed by its own structural features without requiring additional complex attachment mechanisms.
3Ease of operation
If a hook is provided on the filter for gripping and pulling, then filter removal is enabled, but the hook is difficult to find or latch onto in vivo and may be covered by cellular growth
Solution Approach 1:
The retrieval mechanism extracts the engagement feature from the filter itself and places it in the retrieval device. Instead of having a hook on the filter that is hard to find, the bead on the cable serves as the active engagement element that can be maneuvered through the filter gaps to capture the struts.
Solution Approach 2:
Instead of having the filter provide a gripping feature (hook) that is hard to access, the inversion approach uses a retrieval device with a bead that actively seeks out and passes through the filter gaps to engage the struts from within the filter structure.
4Strength
If the bead diameter is larger than filter gaps, then the bead can engage the filter struts, but the bead cannot pass through the gaps to reach the struts
Solution Approach 1:
The bead diameter is dynamically selected to be larger than the strut thickness but smaller than the gap width. This dynamic sizing allows the bead to pass through the gaps to reach the struts while maintaining sufficient diameter to engage and capture the struts effectively for retrieval.
Data Source
AI summary
There are disclosed embodiments of a system for retrieving a filter device from within a patient. A tube or sheath and one or more cables or other elongated members, which include a protrusion such as a bead at or adjacent a distal end, are movable with respect to each other. When the tube or sheath is adjacent a filter device, the cable or elongated member is extended so that the protrusion is between or through wires of the filter, and the protrusion is engaged to or between two or more of the wires. The filter is placed within the tube or sheath, as by retracting the cable or elongated member to pull the filter, by moving the tube or sheath over the cable or elongated member while it engages the filter under tension, or both.