Prosthesis Deployment System Sheath Withdrawal and Valve Design
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Solution Overview
Problem
Existing prosthesis deployment systems face challenges such as difficulty in withdrawing the outer sheath due to tight fit, inadequate gripping surface, kinking of flexible sheaths, and the need for separate trigger wires for retaining and releasing prosthesis ends, as well as inadequate haemostatic valve assemblies that cannot seal across a wide range of device diameters.
Innovation Solution
A prosthesis deployment system with a flexible, kink-resistant sheath and a trigger wire release mechanism that allows for controlled release of prosthesis ends without removing the trigger wire, combined with a haemostatic valve assembly featuring a disc valve and iris-type valve for effective blood loss control across varying device diameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the outer sheath fits tightly over the dilator to maintain shape during delivery, then the structural integrity and shape maintenance is improved, but the ease of withdrawal of the sheath deteriorates
Solution Approach 1:
The outer sheath is divided into two distinct portions: a proximal portion with a first diameter and a distal portion with a second diameter. This segmentation allows the proximal portion to maintain structural integrity while the tapered transition facilitates easier withdrawal by reducing friction against the dilator.
Solution Approach 2:
Different portions of the outer sheath are given different diameters to perform different functions. The proximal portion has a larger diameter for structural support and shape maintenance, while the distal portion has a smaller diameter that tapers to facilitate smooth withdrawal, creating local variations in geometric properties.
2Adaptability or versatility
If the dilator has a small diameter to fit within the sheath, then the flexibility and navigability is improved, but the gripping surface area deteriorates
Solution Approach 1:
The control member provides an extended gripping surface that projects radially outward from the dilator, adding a new dimension to the gripping interface. This allows the operator to grip the control member with adequate surface area while the dilator itself maintains its small diameter for navigability.
Solution Approach 2:
The control member acts as an intermediary between the operator's hand and the dilator. It provides the necessary gripping surface area while being coupled to the dilator, allowing the operator to control the dilator without directly gripping its small-diameter surface.
3Adaptability or versatility
If the sheath is made flexible to conform to tortuous lumens, then the adaptability to body lumen systems is improved, but the resistance to kinking deteriorates
Solution Approach 1:
The outer sheath is constructed as a flexible shell that can conform to tortuous body lumen systems. The sheath material and structure are designed to provide flexibility for navigation while maintaining sufficient structural integrity to resist kinking during delivery and deployment.
Solution Approach 2:
The sheath is divided into portions with different diameters and potentially different material properties, allowing the proximal portion to provide structural support while the distal portion provides flexibility for navigation through tortuous lumens.
4Device complexity
If the trigger wire is removed to release the prosthesis end, then the release mechanism simplicity is improved, but the procedure convenience deteriorates
Solution Approach 1:
The control member merges multiple functions into a single component: it provides the gripping surface for operator control, serves as the retention mechanism for the prosthesis end, and acts as the release mechanism. By pulling the control member, the operator simultaneously controls the dilator position and releases the prosthesis end without needing to remove separate trigger wires.
Solution Approach 2:
The control member is a multi-functional component that performs multiple roles: it provides the gripping interface, maintains dilator position during sheath withdrawal, retains the prosthesis end in the correct position, and serves as the trigger for prosthesis release. This universal component eliminates the need for separate trigger wires.
Data Source
Figure 1
Figure 2
Figure 2A
AI summary
An introducer (1, 2, 3) for a prosthesis (20), comprises an elongate pusher (41) for the prosthesis, a flexible sheath (30) sliding over the pusher, and a control member (81) which is disposed on a proximal portion of the pusher and which is used by an operator to control the portion of the prosthesis while the sheath is being withdrawn.