Stent Graft Delivery Apparatus with Segmented Sheath Control
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Solution Overview
Problem
Current endovascular stent graft delivery systems face challenges in achieving precise and efficient placement within the vasculature, particularly in minimizing procedural risks and ensuring accurate deployment with minimal patient detriment.
Innovation Solution
A stent graft delivery apparatus featuring a flexible elongate member with a retractable sheath and independent control mechanisms, including a rotary draw wire system and manual slider, allows for controlled and incremental retraction of the sheath for precise placement and rapid deployment of the stent graft within the vasculature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single integrated control mechanism is used for sheath retraction, then device complexity is reduced, but precision and control over deployment timing deteriorates
Solution Approach 1:
The control mechanism is divided into two independent control means: a rotary control means for incremental retraction and a linear control means for rapid deployment. This segmentation allows each control to be optimized for its specific function while maintaining overall system simplicity.
Solution Approach 2:
The system provides dynamic control options by allowing the operator to switch between incremental rotary control and rapid linear control based on the deployment stage. The control mechanism adapts its mode of operation to match the procedural requirements at different times.
2Productivity
If rapid sheath retraction is used for efficient deployment, then productivity increases, but precision and control over placement position deteriorates
Solution Approach 1:
The control system separates rapid deployment capability from precise positioning control. The linear control means enables rapid sheath retraction when needed, while the rotary control means provides fine-adjustment capability for precise placement, allowing both speed and accuracy to coexist.
Solution Approach 2:
The system allows preliminary positioning using incremental rotary control to achieve accurate placement, then switches to rapid linear control for final deployment. This preliminary action ensures precision is established before speed is utilized for completion.
3Manufacturing precision
If incremental sheath retraction is used for precise placement, then placement accuracy improves, but procedural time and complexity increase
Solution Approach 1:
The control mechanism dynamically adapts its operation mode based on procedural needs. During positioning phases, incremental rotary control provides precision. During deployment phases, linear control enables rapid retraction, optimizing the balance between accuracy and time consumption at each stage.
Solution Approach 2:
By segmenting the control into two independent means with different speed characteristics, the system can allocate time efficiently - using slower incremental control when precision is critical and faster linear control when time is critical, minimizing overall procedural duration.
4Measurement precision
If complex control mechanisms are used for precise deployment control, then placement precision improves, but ease of operation deteriorates
Solution Approach 1:
The control mechanism is segmented into two simple, independent controls with distinct operational modes. The rotary control provides fine adjustment through simple rotation, while the linear control provides rapid movement through straightforward linear actuation. This segmentation maintains simplicity while achieving precise control.
Solution Approach 2:
Each control means is optimized for its specific function: the rotary control is designed for fine incremental adjustments during positioning, while the linear control is designed for rapid deployment. This local optimization of control characteristics improves ease of operation for each specific task.
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
This apparatus enables precise and efficient placement of stent grafts, reducing procedural complexity and minimizing patient risk by providing fine control over sheath retraction and deployment, thus facilitating effective treatment of vascular anomalies like aneurysms with improved accuracy and speed.
Implementation Method 1
A suitable resilience can be achieved by use of a shape-memory material (such as nitinol) to form the stent. By forcing a stent graft comprising a resilient component into a compressed or collapsed and restrained condition within a sheath, energy stored in the resilient component can be used to subsequently re-configure the stent graft to a deployed condition
Implementation Method 2
it is possible to include means for storing energy in the structure of the stent graft e.g. by use of a resilient strut or loop to facilitate movement from a first configuration to a second configuration. A suitable resilience can be achieved by use of a shape-memory material
Data Source
AI summary
The apparatus has a delivery shaft 30 bearing a tubular device constrained within a moveable sheath 36, and a handle comprising a hollow shaft 124 with a static grip 126 and a grip slider 122 movable proximally or distally. The grip slider is connected to a slider block 24 fixed to a sheath hub 6 to which the sheath is fastened. A retraction wheel 120 has a spool 2 for winding a retraction wire 121 connected to a retraction block 20 in contact with the slider block enabling the slider block to be pushed as the retraction block is retracted distally. Initial incremental movement of the retraction block by winding of the retraction wire, moves the slider block and retraction block simultaneously. Subsequently the slider block is movable independently of the retraction block using the grip slider, leaving the retraction block behind.