Dual-Stage Stent-Valve Compression for Damage-Free Loading
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Solution Overview
Problem
The challenge lies in compressing stent-valves for transcatheter delivery without causing damage, particularly for self-expanding types that require large compression forces and are prone to deformation or buckling, while also accommodating multiple sheaths on a delivery catheter.
Innovation Solution
A dual-stage compressor apparatus with a hollow channel for progressive compression and a crimper for additional local crimping, allowing incremental advancement and temporary pinching to facilitate sheath closure, ensuring controlled compression and shape integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a self-expanding stent-valve is compressed using conventional single-stage compression, then the stent-valve can be loaded onto the delivery catheter, but the stent-valve is prone to damage, buckling, or deformation due to large compression forces and nonuniform stress distribution
Solution Approach 1:
The compression process is divided into multiple sequential stages with progressively smaller compression ratios. The first stage compresses the stent-valve with a larger diameter tolerance, the second stage further compresses it with tighter tolerance, and the third stage achieves final compression. This segmentation distributes the total compression force across multiple gentler steps, preventing sudden buckling or deformation that would occur with single-stage compression.
Solution Approach 2:
Before final compression, the stent-valve undergoes preliminary compression stages that gradually reduce its diameter. The hollow channel is preliminarily positioned around the stent-valve, and compression is initiated with controlled force. This preliminary action prepares the stent-valve structure to better withstand the subsequent final compression stage, preventing damage by avoiding abrupt force application.
2Volume of moving object
If large compression forces are applied to compress a self-expanding stent-valve to a small diameter, then the stent-valve can be accommodated within the delivery catheter, but the stent-valve may deform to a non-circular shape or suffer tissue damage
Solution Approach 1:
The hollow channel providing internal support is positioned at specific locations within the delivery catheter, particularly at the distal end where the stent-valve is being compressed. This localized support structure provides regional reinforcement exactly where needed during compression, maintaining circularity and preventing deformation in critical areas while allowing overall diameter reduction.
Solution Approach 2:
The compression process is made dynamic and adaptive through multiple stages with varying compression ratios. The system transitions from coarse compression with larger tolerance to fine compression with tighter tolerance. Each stage adjusts the compression force and hollow channel positioning dynamically, allowing the stent-valve to maintain its circular shape throughout the progressive compression process rather than undergoing abrupt shape changes.
3Adaptability or versatility
If multiple sheaths are used on the delivery catheter to cover different sections of the stent-valve, then selective deployment is enabled, but the available room and possibilities for compressing the stent-valve are limited
Solution Approach 1:
The hollow channel is nested within the delivery catheter structure, and the stent-valve is nested within the hollow channel during compression. This nested arrangement allows the compression apparatus to be integrated within the existing multi-sheath delivery system without requiring external compression equipment. The hollow channel can be positioned and moved within the catheter to provide support during compression while accommodating the space constraints imposed by the multiple sheaths.
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
Enables easy, intuitive, and cost-effective stent valve compression that avoids damage and buckling, facilitating loading onto a multi-sheath delivery catheter with precise control and ease of sterilization.
Implementation Method 1
a first compressor stage for progressively compressing the stent in response to, or in association with, longitudinal advancement of the stent within the hollow channel
Implementation Method 2
a second compressor stage coupled or couplable to the first compressor stage and configured to further compress a portion of the stent after passing through the first compressor stage
Data Source
AI summary
Apparatus (40) for compressing a transcatheter cardiac stent-valve (10) comprises: a first compressor stage (100) including a hollow channel (42) with a tapered interior surface configured for compressing a stent-valve in response to longitudinal advancement of the stent-valve within the channel; and a second compressor stage (102) comprising a crimper for compressing a portion of the stent-valve without longitudinal advancement.