Helical Retrieval Device for Embedded Vena Cava Filters
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Solution Overview
Problem
Existing retrieval systems for implantable medical devices in blood vessels, such as vena cava filters, face challenges in removal due to embedment in vessel walls and interference with subsequent medical procedures, requiring improved methods for safe and effective extraction.
Innovation Solution
A system comprising a balloon catheter and a radially adjustable retrieval device with a helical member, consisting of first and second support rods, allows for inflation to dislodge the device from the vessel wall and radial compression to facilitate retrieval, enabling the removal of embedded filters and other medical devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a permanent filter is implanted in the vena cava to prevent thrombosis and embolism, then patient safety is improved, but the filter interferes with subsequent medical procedures and requires lifelong implantation
Solution Approach 1:
The retrieval device incorporates a radially adjustable helical member that can dynamically change its configuration between a compressed delivery state and an expanded retrieval state. This dynamic transformation allows the device to transition from a non-interfering implantable state to a retrieval-capable state, resolving the contradiction between permanent safety protection and subsequent procedural accessibility
Solution Approach 2:
The helical member's radial dimension is changed by adjusting the spacing between its coils through mechanical compression and expansion. This parameter change enables the helix to transition from a compact delivery configuration to an expanded state that can engage and retrieve the filter, addressing the adaptability issue while maintaining safety
2Reliability
If the filter remains implanted permanently to prevent thrombosis, then embolism risk is reduced, but the filter becomes embedded in the vessel wall making retrieval difficult
Solution Approach 1:
The system performs preliminary actions by first inflating the balloon to dislodge the filter from the vessel wall before engagement by the helical member. This preliminary dislodging action reduces the embedment barrier, making subsequent retrieval by the helix feasible and addressing the ease of operation issue
Solution Approach 2:
The inflated balloon acts as an intermediary between the vessel wall and the helical retrieval member. By temporarily occupying the space and applying outward pressure, the balloon creates clearance that allows the helix to subsequently engage the filter without direct conflict with the embedded portions, facilitating easier retrieval
3Ease of manufacture
If a retrieval device is designed with a fixed helical structure, then manufacturing is simplified, but the device cannot adapt to different filter sizes and positions
Solution Approach 1:
The helical member transitions from a fixed structure to a dynamically adjustable structure where the coil spacing can be modified through mechanical compression and expansion. This dynamic capability allows the same manufactured structure to adapt to different filter sizes and positions, resolving the contradiction between manufacturing simplicity and operational adaptability
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 system effectively retrieves vena cava filters and other embedded medical devices by inflating the balloon to dislodge them from the vessel wall and using the radially adjustable helical member for secure grasping and retraction, addressing the challenges of embedment and interference.
Implementation Method 1
a balloon catheter having a proximal end and a distal end and an inflatable balloon portion disposed at the distal end
Implementation Method 2
radially compressing the helical member around the balloon catheter and the implantable medical device
Data Source
AI summary
A system for retrieving an implantable medical device includes a delivery sheath that houses an inflatable balloon catheter and a retrieval device. The retrieval device includes a first support rod and a second support rod and a helix extending between distal ends of the first support rod and the second support rod. The inflatable balloon catheter is translatable into a position between the implantable medical device and a wall of a patient blood vessel. The balloon is inflated to force the device away from the wall. The helical member of the retrieval device is expanded radially be translating the second support rod distally. The helical member is moved over the balloon catheter and the medical device, where rotation of the first support rod will cause the helical member to radially compress to trap the balloon catheter and medical device therein for subsequent retrieval from the body.