Retainer System for Transcatheter Heart Valve Delivery
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Solution Overview
Problem
Conventional delivery systems for self-expanding prosthetic heart valves face challenges such as stent strut damage or deformation due to high frictional forces during deployment and resheathing, making it difficult to reposition the valve accurately without causing damage.
Innovation Solution
A catheter assembly with a distal sheath and retainer system that includes a pusher with recesses and a holder with ribs, allowing for controlled deployment and resheathing of the valve by engaging the stent junctions and cell openings, reducing frictional forces and preventing stent deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional delivery systems are used for self-expanding valves, then the valve can be delivered and deployed, but high frictional forces during unsheathing cause high axial forces that may damage or deform the stent struts
Solution Approach 1:
The patent introduces retention members as intermediary elements that engage with the stent struts and transfer forces away from critical areas. These retention members act as mediators between the delivery system and the stent, distributing axial forces along the stent length rather than concentrating them at vulnerable strut regions, thereby preventing damage during unsheathing and deployment
Solution Approach 2:
The delivery system is segmented into multiple functional components including a distal sheath for covering the stent, retention members for engaging specific stent struts, and a pusher mechanism. This segmentation allows independent control of each function, enabling the system to manage frictional forces through coordinated action of separate components rather than a single monolithic structure
2Ease of operation
If the valve is fully deployed, then it expands to full size, but the diameter becomes larger than the sheath making resheathing impossible or difficult
Solution Approach 1:
The patent employs dynamic control of the retention members, which can be engaged or disengaged from the stent struts as needed. During deployment, retention members maintain engagement to control expansion; when resheathing is required, the retention members can be released to allow the stent to collapse back into the sheath. This dynamic engagement/disengagement mechanism enables reversible deployment states
Solution Approach 2:
The retention members are pre-positioned and pre-engaged with the stent struts before deployment occurs. This preliminary engagement ensures that when the sheath is withdrawn, the retention members are already in place to control the stent expansion process, and can be quickly disengaged if resheathing needs to be performed, enabling rapid response to positioning requirements
3Measurement precision
If the valve needs to be repositioned after deployment, then the user must resheath and reposition, but high frictional forces make this process difficult and may cause stent damage
Solution Approach 1:
The retention members serve as intermediaries that facilitate controlled interaction between the delivery system and stent during repositioning. By engaging specific stent struts, they provide precise mechanical leverage for adjusting valve position while distributing forces to prevent strut damage, enabling accurate repositioning without the high frictional forces that would otherwise occur during manual manipulation
Solution Approach 2:
The system changes the mechanical parameters of the stent-delivery interface by introducing retention members with specific engagement geometries. These members alter the friction characteristics and force distribution parameters, reducing the axial forces required for repositioning while maintaining secure engagement, thereby enabling precise positioning adjustments without stent damage
Data Source
AI summary
A delivery device 10 for a collapsible prosthetic heart valve includes a catheter assembly 16 including a shaft 26 around which a compartment 23 is defined, the compartment 23 being adapted to receive the valve in an assembled condition, and a retainer 30 including a pusher 32 and a holder 34 adapted to retain a stent portion 106 of the valve. The catheter assembly 16 also includes a distal sheath 24 adapted to selectively cover and uncover the compartment 23 and the valve, the distal sheath 24 extending around the shaft 26 at least when the distal sheath 24 covers the compartment 23. The pusher 32 includes one or more recesses 40 in a retention edge 33 thereof, each recess 40 being adapted to receive a junction 107 at an end of the stent portion 106 of the valve. The holder 34 includes one or more elongated ribs 50, each rib 50 being adapted to fit into a cell opening 108 of the stent portion 106 of the valve.