Steerable Stent Delivery Shaft Using Shape Memory Polymer Actuation
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Solution Overview
Problem
Current stented prosthesis delivery devices face challenges in navigating tortuous and tight anatomical tracks without causing undue stress on the vasculature, particularly in patients with complex or frail anatomy, due to their size and stiffness, which can lead to anatomical trauma and embolism risks.
Innovation Solution
A delivery device with a handle assembly, outer shaft, inner shaft, and actuation bodies, including shape memory polymers, that allows for controlled deflection and steering of the outer shaft to navigate anatomical bends, minimizing contact stress and trauma, using electrical stimulation to activate the actuation bodies for precise movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the delivery device uses a large profile and stiff shaft to maintain column strength for force transfer, then the pushing force can be effectively transferred to forward motion, but the device cannot navigate tortuous and tight anatomical tracks without causing undue stress on the vasculature
Solution Approach 1:
The delivery device shaft is divided into multiple segments with varying stiffness characteristics. The proximal shaft maintains higher stiffness for force transfer, while the distal shaft becomes progressively more flexible to navigate tortuous anatomy. This segmentation allows the device to simultaneously provide sufficient column strength for pushing force transfer while reducing stress on the vasculature in distal regions.
Solution Approach 2:
Different portions of the delivery device shaft are assigned different mechanical properties. The proximal section maintains higher rigidity for effective force transmission from the operator, while the distal section incorporates flexible materials or structures that can conform to tight anatomical bends. This local differentiation of mechanical properties resolves the contradiction between needing strength for force transfer and flexibility for safe navigation.
2Stability of the object's composition
If the delivery device uses a stiff shaft to maintain structural integrity, then the device can transfer pushing force effectively, but the device cannot follow the natural curvature of tortuous vasculature
Solution Approach 1:
The delivery device incorporates dynamic elements that allow the shaft to change its mechanical characteristics during navigation. The shaft can transition from a more rigid state during force application to a more flexible state during navigation through tortuous anatomy. This dynamic adaptability allows the device to maintain structural integrity when needed while following natural vasculature curves when required.
Solution Approach 2:
The delivery device employs a nested construction with multiple concentric shafts or components. The inner shaft provides structural integrity and force transfer, while outer flexible layers or coatings allow the device to conform to anatomical curves. This nested architecture enables the device to simultaneously maintain structural integrity and adapt to tortuous vasculature by combining rigid and flexible elements in a nested configuration.
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 controlled and efficient delivery of stented prostheses, such as heart valves, through tortuous paths with reduced anatomical stress and trauma, improving navigation and deployment precision while maintaining structural integrity.
Implementation Method 1
The actuation body is operable to deflect the outer shaft in response to the delivered stimulation. In some embodiments, the actuation body includes or comprises a shape memory polymer, and the delivered stimulation is an electrical current.
Data Source
AI summary
A stented prosthesis delivery device with steering capabilities. One or more actuation bodies (e.g., shape memory polymer) are located at a distal region of the delivery device, and are selectively stimulated by a user (e.g., via a controller or joy stick at the device's handle) to effect desired steering.