Collapsible Prosthetic Heart Valve Frame With Retrieval Tethers
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Solution Overview
Problem
Designing a prosthetic heart valve that can collapse to a small diameter without damaging flexible leaflets and can be re-collapsed for repositioning or removal while effectively anchoring at the implant site is a challenging task in existing technologies.
Innovation Solution
A frame structure for a prosthetic heart valve featuring a plurality of Y-shaped structures in an annular array, with collapsible and re-expandable connecting structures, aortic and annulus portions, and strut members that allow for controlled expansion and anchoring, utilizing nitinol for elasticity and tissue integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the valve is collapsed to a small diameter for delivery, then the valve can be delivered through catheters and delivery apparatus, but the flexible leaflets may be damaged during collapse
Solution Approach 1:
The valve frame is segmented into multiple expandable cells or struts that can be independently controlled during expansion. This segmentation allows the frame to collapse uniformly to a small diameter for delivery while providing multiple support points that prevent excessive folding or crushing of the leaflets during the collapse and expansion cycles
Solution Approach 2:
The delivery apparatus incorporates cushioning or protection mechanisms that are in place before the valve is deployed. These mechanisms protect the leaflets during the collapse and delivery process, preventing damage before the valve reaches the implant site where it will be expanded and functionalized
2Adaptability or versatility
If the valve is re-collapsed for repositioning or removal, then the valve can be repositioned or removed from the patient, but the structural integrity may be compromised
Solution Approach 1:
The valve frame employs dynamic materials such as nitinol that can reversibly change their mechanical properties. These materials allow the frame to be collapsed for repositioning or removal and then return to its original strong, load-bearing configuration after expansion, maintaining structural integrity through multiple collapse-expansion cycles
Solution Approach 2:
The frame structure utilizes phase-changing materials or materials with reversible property changes that allow transition between a collapsed low-strength state during delivery/repositioning and an expanded high-strength state during function. This parameter change enables the frame to withstand repeated mechanical cycling without permanent damage
3Reliability
If the valve is expanded to full size for operation, then the valve can effectively anchor native tissue, but the valve cannot be easily retrieved or repositioned
Solution Approach 1:
The delivery apparatus maintains control over the expanded valve through preliminary action mechanisms such as retention members, tethers, or mechanical interlocks that engage with the frame before full expansion and tissue anchoring occurs. These mechanisms allow the operator to retrieve or reposition the valve if needed, providing a window of opportunity for correction before permanent anchoring
4Stability of the object's composition
If rigid structures are used to maintain valve shape during collapse, then the valve structure is maintained, but the flexible leaflets are damaged
Solution Approach 1:
The valve employs a flexible membrane or thin-walled structure that can conform to the collapsed configuration without rigid support. This flexible shell maintains the overall valve shape and protects the leaflets by providing a compliant envelope that moves with the frame during collapse and expansion, preventing the leaflets from being crushed or folded excessively
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
The frame structure maintains structural integrity during collapse and expansion, ensuring reliable anchoring and repositioning capabilities, while minimizing interference with native tissues and facilitating easy retrieval and re-deployment.
Implementation Method 1
Elastic re-expansion may be achieved by using a springy metal such as nitinol in the valve
Implementation Method 2
Plastic expansion may be achieved, for example, by inflating a balloon inside the valve
Data Source
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AI summary
A frame structure for a collapsible and re-expandable prosthetic heart valve. The frame structure includes an annular annulus portion that is configured for implanting in or near a patient's native heart valve annulus. This annulus portion of the frame structure may include a plurality of annularly spaced Commissure post structures interconnected by connecting structures. The commissure post structures may be more resistant to annular collapse than the connecting structures. In the case of a prosthetic aortic valve, the frame structure may also include an annular aortic portion. The aortic portion may include a plurality of attachment points (for tethers) closest to the annulus portion. Such attachment points and tethers can facilitate re-collapse of a partly deployed valve in the event of a need to reposition or remove the valve.