Staged Deployment Mechanism for Transcatheter Heart Valve Repositioning
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Solution Overview
Problem
Conventional delivery systems for self-expanding prosthetic heart valves face challenges in controlling partial deployment and repositioning, as they often result in accidental full deployment before verifying the valve's optimal position, making it difficult to resheathe and reposition the valve.
Innovation Solution
A delivery device with a catheter assembly and operating handle that includes a carriage assembly and a distal sheath, allowing for controlled movement between closed and open conditions, enabling precise partial and full deployment, and featuring a resheathing lock mechanism to prevent accidental full deployment, allowing for repositioning of the valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the valve is deployed to allow repositioning, then the ability to resheathe and reposition is improved, but the risk of accidental full deployment increases
Solution Approach 1:
The delivery system is divided into distinct functional components: a sheath that can be partially retracted, a valve with staged deployment capability, and a locking mechanism. This segmentation allows the operator to control deployment in stages - first exposing part of the valve for positioning, then completing deployment - thereby enabling repositioning while preventing accidental full deployment through the locking mechanism
Solution Approach 2:
A locking mechanism acts as an intermediary between the sheath retraction action and valve deployment. This intermediary component prevents direct coupling between sheath movement and valve expansion, allowing the operator to retract the sheath for positioning without automatically triggering full valve deployment, thus reducing the risk of accidental full deployment while maintaining repositioning capability
2Reliability
If the valve is fully deployed to ensure proper expansion, then the valve functionality is improved, but the ability to resheathe and reposition is lost
Solution Approach 1:
The system employs dynamic control where the sheath can be retracted to different extents and locked at intermediate positions. The valve itself has dynamic deployment characteristics - it can be partially expanded while still covered by the sheath, then fully expanded once positioned. This dynamic capability allows the operator to achieve proper valve expansion while retaining the option to resheathe if repositioning is needed
Solution Approach 2:
The sheath is retracted partially before full valve deployment to allow preliminary positioning verification. This preliminary action enables the operator to check valve position and orientation before completing the deployment process, ensuring proper expansion while maintaining the ability to resheathe and reposition if the preliminary positioning is unsatisfactory
3Speed
If the sheath is retracted to deploy the valve, then the deployment speed is improved, but the control over partial deployment is reduced
Solution Approach 1:
The locking mechanism provides feedback control by allowing the operator to retract the sheath, assess the valve position, and then decide whether to proceed with full deployment or resheathe. This feedback loop enables controlled partial deployment at high speed while maintaining precision over the deployment extent through the operator's ability to lock at intermediate positions
Data Source
AI summary
A delivery device for a collapsible heart valve includes an operating handle and a catheter assembly. The operating handle includes a frame defining a movement space therein, a carriage assembly moveable in a longitudinal direction within the movement space, and a coupler having locked and unlocked conditions, the coupler being operatively connected to the carriage assembly for movement therewith. The catheter assembly includes a shaft around which a valve-receiving compartment is defined, the shaft being operatively connected to one of the frame or the carriage assembly, and a distal sheath operatively connected to the carriage assembly for movement therewith between a closed condition adapted to maintain the valve in the compartment and an open condition adapted to fully deploy the valve.