Delivery Device With Distal Sheath Deployment for Curved Paths
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Solution Overview
Problem
Conventional delivery devices for stented prosthetic mitral valves face challenges in navigating curved anatomical paths due to their stiffness, leading to unstable deployment and positional inaccuracies, particularly in the mitral valve's complex anatomy, which can result in fatal complications.
Innovation Solution
A delivery device with a sheath tube design that allows for distal end deployment, incorporating a guide tip, inner tubular core, and a bending controllable tube to navigate curved paths while ensuring high coaxiality and stability, allowing for sequential release of implant portions to facilitate accurate positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the sheath tube is made stiff to resist radial forces from the stent, then the structural strength is improved, but the ability to navigate curved anatomical paths deteriorates
Solution Approach 1:
The delivery device is divided into multiple functional segments: a stiff distal section (sheath tube with guide tip) to resist stent radial forces, and a flexible proximal section (bending controllable tube) to navigate curved anatomical paths. This segmentation allows each segment to optimize its mechanical properties for its specific function.
Solution Approach 2:
Different parts of the delivery device have different stiffness characteristics. The distal end containing the sheath tube and guide tip is designed to be stiff for structural support, while the proximal bending controllable tube is designed to be flexible for navigation. This local differentiation of mechanical properties resolves the contradiction between strength and adaptability.
2Manufacturing precision
If the delivery catheter maintains a fixed geometrical configuration to ensure positional accuracy, then the deployment precision is improved, but the ability to retract through curved paths deteriorates
Solution Approach 1:
The delivery catheter is segmented into a fixed distal portion (sheath tube with guide tip) that maintains geometrical configuration for positional accuracy, and a flexible proximal portion (bending controllable tube) that can adapt to curved paths during retraction. This segmentation allows both requirements to be satisfied simultaneously.
3Stability of the object's composition
If the sheath tube is made long to provide sufficient support, then the structural stability is improved, but the radius of curvature for bending increases beyond anatomical constraints
Solution Approach 1:
The delivery device is segmented such that the long bending controllable tube is separated from the short stiff sheath tube. This allows the overall device to have sufficient length for navigation while the functional deployment portion remains short enough to bend within anatomical constraints.
Solution Approach 2:
The bending capability is localized to the proximal controllable tube section, while the distal sheath tube maintains a short length with high stiffness. This local differentiation allows the system to achieve both long overall length for reach and short local length for maneuverability.
4Ease of manufacture
If the outflow portion is released before the inflow portion during deployment, then the self-expansion mechanism works, but the positional accuracy of the inflow portion deteriorates
Solution Approach 1:
The deployment sequence is inverted compared to conventional designs. Instead of releasing the outflow portion first, the inflow portion is released and positioned against the annulus first, followed by release of the outflow portion. This inversion ensures that the critical inflow positioning is established before the stent fully expands.
Solution Approach 2:
The inflow portion is preliminarily positioned against the annulus before complete stent expansion occurs. This preliminary positioning action ensures accurate alignment is achieved while the stent is still partially constrained, preventing positional deviations that would occur if positioning attempted after full expansion.
Data Source
AI summary
A delivery device (1, 1′) for loading, delivering and deploying an implant (2) includes a handle (18), an inner tubular core (11), a sheath tube (13) and a guide tip (12). The inner tubular core (11) is coupled, at a proximal end thereof, to an inner tubular core actuation member arranged in the handle (18), and the guide tip (12) is disposed at a distal end of the inner tubular core (11) and fixedly connected to a distal end of the sheath tube (13). The sheath tube is (13) sleeved over the inner tubular core (11). Here, the proximal end of each component refers to the end thereof closer to the handle (18), while the distal end thereof is the end farther away from the handle (18). As the sheath tube (13) is fixedly connected, at the distal end thereof, to the guide tip (12), the implant (2) is loaded at the proximal end of the sheath tube (13) in the delivery device (1, 1′). During deployment of the implant (2), the sheath tube (13) is caused to move toward distal end, that is, the sheath tube (13) continues moving toward a target site for the implant (2), rather than moves backward to the handle (18). This can effectively avoid the problems that may arise from retraction of the sheath tube (13) through a three-dimensionally curved path, such as unstable or even faulty deployment of the implant (2), thus allowing deployment of the implant (2) with enhanced quality.