Stent Delivery Core Assembly With Undercut Proximal Restraint
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Solution Overview
Problem
Conventional stent delivery systems face issues with proximal restraints that can lead to stent migration due to rounded surfaces, causing damage to catheters and preventing proper stent deployment, especially in narrow and tortuous vasculature.
Innovation Solution
The introduction of a proximal restraint with an undercut portion or recess to inhibit stent migration, ensuring the stent remains in place during advancement and deployment, using a core assembly with a bumper section and distal section to maintain precise geometric alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional proximal restraints with rounded surfaces are used, then the stent delivery system is easier to manufacture, but the stent may migrate proximally causing damage to catheters and preventing proper deployment
Solution Approach 1:
The proximal restraint transitions from a symmetric rounded surface to an asymmetric geometry featuring a flat distal end face and an undercut portion. The flat face provides a stable stopping surface for the stent, while the undercut portion (with radial dimension smaller than the stent's radial dimension) creates a mechanical interference fit that prevents proximal migration. This asymmetric design resolves the contradiction by providing reliable stent positioning without requiring overly complex manufacturing processes.
Solution Approach 2:
The invention adds a radial dimension constraint through the undercut portion, which extends radially inward from the flat distal end face. This creates a three-dimensional geometric feature that prevents proximal movement of the stent by utilizing radial interference. The undercut portion's smaller radial dimension compared to the stent creates a mechanical lock that operates in the radial dimension, thereby preventing unwanted motion in the longitudinal dimension.
2Reliability
If the proximal restraint has a larger radial dimension to prevent stent migration, then stent positioning is improved, but the device complexity increases
Solution Approach 1:
The proximal restraint is segmented into distinct functional portions: a flat distal end face for providing a stable stopping surface, an undercut portion for preventing proximal migration through radial interference, and a proximal section for structural support. This segmentation allows each portion to be optimized for its specific function while maintaining overall simplicity. The undercut portion is further segmented into a first portion with a first radial dimension and a second portion with a second radial dimension, enabling precise control over stent interaction.
Solution Approach 2:
Different portions of the proximal restraint are given different local geometric qualities tailored to their specific functions. The flat distal end face provides a smooth, flat surface for stable contact. The undercut portion provides a tighter, interference-fit geometry for migration prevention. The proximal section provides structural support with appropriate rigidity. This local differentiation of geometric qualities allows the restraint to perform multiple functions without requiring overall structural complexity.
3Reliability
If the bumper section has a larger radial dimension, then stent confinement is improved, but the difficulty of navigating tortuous vasculature increases
Solution Approach 1:
The core assembly is designed with dynamic flexibility to accommodate the tortuous nature of vasculature. The proximal restraint includes a flexible connection between the bumper section and the elongate member, allowing the assembly to bend and conform to vessel curvature during navigation. Once positioned, the bumper section's radial dimensions provide stable stent confinement. This dynamic design allows the system to transition from a flexible navigation state to a stable deployment state.
Solution Approach 2:
The bumper section utilizes a tiered radial dimension structure with a first radial dimension larger than the stent and a second radial dimension smaller than the stent. This creates a three-dimensional confinement geometry that secures the stent in the longitudinal dimension while allowing flexibility in the radial dimension for navigation. The elongate member extends through the core assembly, providing a flexible backbone that can navigate tortuous paths while maintaining stent confinement through the bumper's geometric structure.
Data Source
AI summary
A stent delivery system can include a core assembly sized for insertion into a corporeal lumen and configured for advancing a stent toward a treatment location in the corporeal lumen. The core assembly can include a proximal restraint having a bumper section, a distal section distal to the bumper section, a lumen extending through the bumper and distal sections, and an undercut section including a recess at least partially surrounding the lumen. The recess can abut and/or be formed in the bumper and/or distal sections.