Force limiting mechanism for prosthetic heart valve delivery apparatus
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Solution Overview
Problem
Existing prosthetic heart valve deployment technologies risk exerting excessive radial force on the native heart valve annulus, potentially leading to rupture during expansion.
Innovation Solution
A force limiting mechanism within a delivery apparatus that includes a pivot arm and a base portion, configured to pinch the actuation member between them when excessive force is applied, preventing further movement and limiting the expansion force to a predetermined threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a mechanical actuator is used to expand the prosthetic valve, then the valve can be deployed to its functional size, but excessive radial force may be applied to the native annulus causing rupture
Solution Approach 1:
The force limiting mechanism is pre-configured with a predetermined force threshold before the procedure. The pivot arm and base portion are positioned to engage the actuation member at a specific geometric relationship, establishing the force limit in advance. When deployed, this pre-set mechanism automatically engages to prevent excessive force application.
Solution Approach 2:
The pivot arm acts as an intermediary mechanical element between the actuation member and the base portion. It transmits and limits the force from the actuation member, converting the pulling force into a controlled radial expansion force while capping the maximum force at a predetermined level through its geometric constraints.
2Strength
If the actuation member is allowed to move freely, then full expansion force can be applied, but the risk of annulus rupture increases
Solution Approach 1:
The force limiting mechanism changes the force parameter from uncontrolled to controlled by introducing a maximum force threshold. The pivot arm geometry is designed so that the mechanical advantage changes as the arm pivots, naturally limiting the output force to a predetermined maximum value regardless of how much pull is applied to the actuation member.
Solution Approach 2:
The force limiting mechanism provides a safety cushion by pre-establishing a maximum force barrier. The pivot arm and base portion are configured to engage before excessive force can be transmitted, effectively cushioning the system against force overload that could cause annulus rupture.
3Object-affected harmful factors
If a force limiting mechanism is added to the delivery apparatus, then excessive force is prevented, but the device complexity increases
Solution Approach 1:
The force limiting mechanism is segmented into distinct functional components: the pivot arm, the base portion, and the actuation member interface. This segmentation allows each component to be optimized independently and facilitates assembly, maintenance, and adjustment of the force limiting function without complicating the entire delivery system.
Solution Approach 2:
The force limiting mechanism is self-regulating through the geometric relationship between the pivot arm and base portion. Once configured with the predetermined force threshold, the mechanism automatically engages and disengages based on the applied force, requiring no active control or additional complexity in the operator interface.
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
Prevents excessive force from being applied to the native heart valve annulus, ensuring safe and controlled expansion of the prosthetic heart valve.
Implementation Method 1
The force limiting mechanism can comprise a pivot arm and a base portion. The pivot arm can be pivotably coupled to the base portion. The actuation member can be movably coupled to the pivot arm such that a force applied to the actuation member causes the pivot arm to pivot relative to the base portion.
Implementation Method 2
The force limiting mechanism can be configured to pinch the actuation member between the pivot arm and the base portion when the force applied to the actuation member exceeds a predetermined force, thereby preventing proximal movement of the actuation member.
Data Source
AI summary
A medical assembly can include a radially expandable prosthetic heart valve and a delivery apparatus. The delivery apparatus can include a handle, an actuation member, and a force limiting mechanism within the handle including a pivot arm coupled to a base portion. The actuation member can apply a proximally directed force to the prosthetic valve to cause the valve to expand. The actuation member can be coupled to the pivot arm such that a force applied to the actuation member causes the pivot arm to pivot. The force limiting mechanism can pinch the actuation member between the pivot arm and the base portion when the force applied to the actuation member exceeds a predetermined force to prevent proximal movement of the actuation member and can allow proximal movement of the actuation member to produce radial expansion of the prosthetic valve when the force applied is less than the predetermined force.