Superelastic Annuloplasty Ring for Minimally Invasive Delivery
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Solution Overview
Problem
Current annuloplasty ring technologies for mitral and tricuspid valve repair require invasive procedures due to their size and rigidity, making minimally invasive surgery challenging as they cannot be easily delivered through small surgical openings or tubes.
Innovation Solution
A minimally-invasive annuloplasty ring with a superelastic metal core member that can be straightened to pass through small openings, featuring a C-shaped design with varying radial thickness and curvature to maintain stiffness while allowing elastic deformation below the yield strain of Nitinol, enabling delivery through catheters or small tubes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the annuloplasty ring is made rigid to maintain structural integrity, then it can support functional changes during the cardiac cycle, but it cannot be delivered through small surgical openings or tubes
Solution Approach 1:
The patent utilizes the superelastic property of Nitinol material, which allows the annuloplasty ring to change its mechanical parameters (from rigid to flexible) temporarily during delivery, then return to its original rigid structural integrity after implantation. This parameter change enables the ring to be compressed and straightened for catheter delivery while maintaining the necessary structural strength for valve repair function
Solution Approach 2:
The annuloplasty ring transitions from a static rigid structure to a dynamic system that can adapt its flexibility state. During delivery, the ring is dynamically transformed into a flexible, straightened configuration that can pass through small openings. After implantation, it dynamically returns to its predetermined rigid arc shape to provide structural support
2Ease of operation
If the annuloplasty ring is made flexible to enable delivery through catheters, then it can be inserted through small openings, but it loses the rigidity needed to maintain valve annulus structure
Solution Approach 1:
The superelastic Nitinol material enables reversible parameter changes in the ring's mechanical properties. When delivered through the catheter, the ring exhibits flexible behavior due to elastic deformation. Once deployed at the valve annulus, it automatically recovers its rigid structural form, maintaining the necessary strength to support the valve annulus during cardiac cycles
Solution Approach 2:
The ring is pre-configured with a specific arc shape and structural geometry before delivery that is designed to provide optimal structural support. This preliminary configuration is temporarily deformed during delivery but automatically restored after implantation, ensuring the ring maintains its intended structural support capability from the moment of deployment
3Ease of manufacture
If traditional sternotomy is used to access the thoracic cavity, then the annuloplasty ring can be easily implanted, but the procedure has significant morbidity and mortality
Solution Approach 1:
The patent introduces a catheter as an intermediary delivery system that enables minimally invasive access to the heart. The annuloplasty ring is delivered through this intermediary catheter through small peripheral vessels or openings, avoiding the need for direct surgical access through sternotomy. This intermediary approach significantly reduces surgical trauma while maintaining the ability to implant the ring effectively
Solution Approach 2:
The delivery system is segmented into separate components: the catheter for access and the annuloplasty ring for implantation. This segmentation allows the ring to be delivered through a small catheter and then deployed at the target site, separating the access function from the implantation function and enabling minimally invasive surgery
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 the delivery of the annuloplasty ring through small surgical openings or tubes, maintaining structural integrity and reducing morbidity and mortality associated with traditional invasive procedures by allowing temporary flexion into a linear shape for minimally invasive implantation.
Implementation Method 1
The inner core member is a superelastic metal so that it can be straightened out and delivered through an access tube. The curvatures and thicknesses around the core member are selected so that the strain experienced when straightened does not exceed 7-8%.
Implementation Method 2
A middle or posterior portion of the core member has a thicker radial dimension than a pair of free end regions terminating on an anterior side of the core member. The radial thickness smoothly transitions between the posterior portion and the end regions.
Data Source
AI summary
A minimally-invasive annuloplasty ring for implant at a mitral annulus. The annuloplasty ring has an inner core member with a C-shaped plan view that generally defines an oval with a major axis and a minor axis, and is symmetric about the minor axis. A posterior portion of the core member bisected by the minor axis has a thicker radial dimension than a pair of free end regions terminating on an anterior side of the core member. The radial thickness smoothly transitions between the posterior portion and the end regions. The inner core member may be covered with a fabric, and is a superelastic metal so that it can be straightened out and delivered through an access tube. The curvatures and thicknesses around the core member are selected so that the strain experienced when straightened does not exceed 7-8%.