Inferior Vena Cava Filter Retrieval Using Dual-Window Sheath
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Solution Overview
Problem
Existing methods for removing implanted vena cava filters are limited, as they typically require approaching the filter from the superior side, making alternative removal methods necessary when the typical approach is impossible or undesirable.
Innovation Solution
A device with an outer and inner sheath, featuring radial windows and a snare tool with a guide element and snare loop, allows for inferior retrieval by aligning and overlapping the windows to capture and pull the filter into the inner sheath, facilitating removal from the opposite end of the hub.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a typical superior removal method is used, then the filter can be removed from the hub end, but the method is impossible when approaching from the superior side is not desired or feasible
Solution Approach 1:
The invention inverts the traditional removal approach by enabling inferior retrieval instead of superior removal. The device allows the filter to be captured and pulled upward from the inferior side through radial windows, reversing the conventional direction of filter removal and providing alternative access when superior approach is not feasible.
Solution Approach 2:
The removal device is segmented into multiple functional components including an outer catheter with radial windows, an inner catheter, and a snare system. This segmentation allows each component to perform specific functions: the radial windows provide access paths, the inner catheter supports the snare, and the snare captures the filter, collectively enabling inferior retrieval through coordinated action of discrete elements.
2Adaptability or versatility
If radial windows are provided in the outer catheter for inferior access, then alternative removal path is enabled, but the outer surface smoothness may be compromised
Solution Approach 1:
The inner catheter is designed to be movable relative to the outer catheter, allowing dynamic adjustment of the radial window openings. During filter capture, the inner catheter can be positioned to expose the radial windows for snare access. After capture, the inner catheter moves to cover the radial windows, restoring a smooth outer surface for safe withdrawal through the vasculature.
Solution Approach 2:
The radial windows are pre-positioned in the outer catheter at locations optimized for filter engagement, but their functionality is controlled by the movable inner catheter. This preliminary configuration allows rapid deployment of access paths when needed while maintaining a streamlined profile during non-operational phases, eliminating the need for complex mechanical adjustments during the procedure.
3Reliability
If the inner catheter is made movable to cover the radial opening, then a flush outer surface is formed for safe withdrawal, but the device complexity increases
Solution Approach 1:
The inner catheter is nested within the outer catheter, with the inner catheter's outer surface serving to cover the radial windows of the outer catheter when positioned appropriately. This nesting arrangement allows the simpler inner catheter to perform the protective function of smoothing the outer surface, while the overall device maintains a compact, telescopic structure that minimizes complexity through space-efficient design.
Data Source
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AI summary
A device (100) for inferior retrieval of a vena cava filter (120) includes an outer sheath (102) with a first radial window (112) closer to the distal end than the proximal end of the outer catheter; an inner sheath (104) generally extending movably inside the lumen of the outer sheath and having a second radial window (114); and a snare tool (106) having an elongated guide element extending through the inner sheath and a snare loop (110) distally attached to the guide element. The snare loop is extendable outward through the two radial windows.