Variable-Rigidity Delivery Tube for Aortic Valve Navigation
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Solution Overview
Problem
Current ventricular assist devices face challenges in efficiently navigating the aortic valve and arch due to rigid structures, which can lead to complications during insertion and operation, and there is a need for a device that can provide varying mechanical properties along its length to facilitate smooth passage and optimal blood flow.
Innovation Solution
A left-ventricular assist device with a delivery tube that has varying flexural rigidity along its length, achieved through a combination of materials and structures such as a polyurethane jacket, polyether block amide jacket, and polyamide jacket, along with a braid and coil with varying pick density and pitch, allowing for flexible navigation through the aorta and efficient blood pumping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the delivery tube has high flexural rigidity to maintain structural stability, then the device can resist deformation and maintain shape, but it becomes difficult to navigate through the aortic valve and arch
Solution Approach 1:
The delivery tube is constructed with varying flexural rigidity along its length, with the distal portion having lower rigidity to facilitate navigation through the aortic valve and arch, while proximal portions maintain higher rigidity for structural stability. This gradient structure allows each section to have optimized mechanical properties for its specific functional requirements.
Solution Approach 2:
The delivery tube employs a dynamic flexibility profile where the flexural rigidity changes continuously along the tube length. This dynamic property distribution enables the tube to adapt its mechanical behavior - being more flexible where needed for navigation and stiffer where needed for support, rather than having uniform properties throughout.
2Ease of operation
If the delivery tube is made flexible to navigate through the aorta, then it can traverse the aortic valve and arch easily, but it may elongate or bend excessively during operation
Solution Approach 1:
Different sections of the delivery tube have different flexural rigidity values - the distal section has lower rigidity for easy navigation, while proximal sections have progressively higher rigidity to prevent excessive elongation and bending during the pumping operation. This local differentiation resolves the contradiction between flexibility for navigation and stiffness for stability.
Solution Approach 2:
The delivery tube utilizes composite construction with multiple materials or layers having different mechanical properties. This composite structure allows the tube to exhibit graded flexural rigidity along its length, combining the flexibility needed for navigation with the stiffness required to resist elongation and bending during operation.
3Reliability
If the delivery tube has high flexural rigidity to prevent elongation, then it maintains stable blood flow, but it cannot effectively traverse the aortic arch
Solution Approach 1:
The delivery tube implements spatially varying flexural rigidity where the distal portion (needed for aortic arch traversal) has lower rigidity for flexibility, while the proximal portion (affecting blood flow stability) has higher rigidity. This local quality differentiation allows the tube to satisfy both requirements simultaneously in different locations.
Solution Approach 2:
The delivery tube is effectively segmented into multiple functional zones along its length, with each segment having optimized flexural rigidity for its specific role. The distal segment facilitates navigation, while proximal segments maintain structural integrity and blood flow stability, resolving the contradiction through functional segmentation.
Data Source
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AI summary
Apparatus and methods are provided, including a left-ventricular assist device (20) that includes an impeller (50) configured for insertion into a subject's left ventricle. A delivery tube (142) passes through the subject's aorta, from outside the subject into the left ventricle. The delivery tube (142) includes an outer layer (167) that varies along a length of the delivery tube (142) such that a flexural rigidity of the delivery tube at a first portion (P1) of the delivery tube, which is configured to traverse the aortic valve, is less than the flexural rigidity at a second portion (P2), which is configured to traverse at least a portion of the aortic arch, and the flexural rigidity at the second portion (P2) is less than the flexural rigidity at a third portion (P3), which is configured to traverse the descending aorta. Other applications are also described.