Helical Sheath Structure for BAV Balloon Rewrapping
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Solution Overview
Problem
Existing balloon aortic valvuloplasty (BAV) devices used in transcatheter aortic valve replacement (TAVR) procedures face challenges in effectively rewrapping the balloon after dilation due to their large size, leading to undesired flattening and potential damage to the balloon or introducer sheath.
Innovation Solution
A tubular sheath with helically arranged balloon guide elements, such as ridges or grooves, on its inner surface is used to facilitate the rewrapping of the balloon by guiding it back into a low profile configuration, minimizing damage and ensuring smooth retraction through the introducer sheath.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional smooth-walled sheath is used for balloon delivery, then the device structure is simple, but the balloon cannot be effectively rewrapped after dilation leading to flattening and potential damage
Solution Approach 1:
The sheath incorporates localized helical ridges on its inner surface at the distal end region where balloon rewrapping is needed, while the rest of the sheath maintains a smooth structure. This localized modification enables effective balloon rewrapping without requiring complete structural complexity throughout the entire sheath.
Solution Approach 2:
The sheath structure is segmented into different functional zones: a distal end region with helical ridges for balloon rewrapping and a proximal region with smooth walls for easy insertion and withdrawal. This segmentation allows each region to perform its specific function optimally without compromising the other.
2Shape
If the balloon is pulled proximally into the sheath for rewrapping, then the balloon can be folded into a low profile configuration, but the large size of the balloon causes flattening and potential damage
Solution Approach 1:
The helical ridges on the sheath inner surface create a curved, spiral path that guides the balloon into a compact folded configuration as it is pulled proximally. This curved geometry allows the large balloon to be efficiently packed into a small profile without flattening, reducing the risk of damage during retrieval.
3Strength
If the sheath wall thickness is increased to provide structural support, then the sheath strength is improved, but the push-ability in tortuous anatomies is reduced
Solution Approach 1:
The sheath has non-uniform wall thickness with the distal end featuring thinner walls to enhance flexibility and push-ability in tortuous anatomies, while the proximal end has thicker walls for structural strength and stability during the procedure. This local variation allows the sheath to navigate complex vascular paths while maintaining necessary strength.
Data Source
AI summary
An outer sheath for delivering and re-sheathing an expandable balloon includes a tubular sheath having a distal end and a proximal end, and a plurality of balloon guide elements extending helically along an inner surface of a distal end region of the tubular sheath, where the plurality of balloon guide elements is spaced apart circumferentially. The outer sheath is part of a dilation balloon catheter assembly including a main catheter defining a lumen and a balloon catheter having a balloon fixed to a distal end thereof, where the balloon catheter is slidably disposed within the lumen of the main catheter, and the balloon is configured to move between a folded configuration and an expanded configuration. The plurality of balloon guide elements is configured to facilitate folding of the balloon after expansion when the balloon is pulled proximally into the outer sheath.