Catheter Outer Shaft with Dual Braided Layers for Tortuous Navigation
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Solution Overview
Problem
Traditional surgical methods for implanting medical devices, such as heart valves, require invasive procedures and result in significant patient trauma and long recuperation times, while minimally-invasive delivery systems face challenges in navigating tortuous vasculature due to competing design considerations like flexibility and stiffness.
Innovation Solution
A delivery system comprising a catheter with an outer shaft featuring an inner braided layer, an outer braided layer with lower braid density, an axial spine, and jacket layers of different materials, along with a stability shaft and a capsule that can be actuated to expose the implantable medical device, allowing for improved navigation and deployment within the body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the delivery catheter has a small outer diameter to facilitate navigation through tortuous vasculature, then the ability to navigate through tortuous anatomy is improved, but the axial strength and torsional strength are reduced
Solution Approach 1:
The catheter incorporates multiple braided layers with different material compositions and braid densities. The inner braided layer has a higher braid density providing flexibility, while the outer braided layer has a lower braid density providing axial and torsional strength. This composite structure allows the catheter to simultaneously achieve navigation capability through tortuous anatomy and maintain necessary mechanical strength.
Solution Approach 2:
The catheter is divided into multiple functional layers with distinct properties. The inner braided layer and outer braided layer are segmented as separate structural components, each optimized for specific functions. The inner layer focuses on flexibility for navigation, while the outer layer focuses on strength for force transmission, resolving the contradiction between these competing requirements.
2Ease of operation
If the delivery catheter has high flexibility to navigate tortuous vasculature, then the ease of navigation is improved, but the axial strength and torsional strength are reduced
Solution Approach 1:
The catheter uses a composite structure with an inner braided layer optimized for flexibility (higher braid density) and an outer braided layer optimized for strength (lower braid density). This allows the catheter to be both easy to navigate through tortuous vasculature and strong enough to withstand manipulation forces.
Solution Approach 2:
Different portions of the catheter wall have different braid densities tailored to their specific functions. The inner layer has higher braid density for flexibility where navigation is critical, while the outer layer has lower braid density for strength where force transmission is critical. This local differentiation resolves the contradiction between flexibility and strength.
3Strength
If the delivery catheter has high axial strength to withstand pushing and pulling forces, then the force transmission capability is improved, but the flexibility to navigate tortuous vasculature is reduced
Solution Approach 1:
The catheter employs a composite braided structure where the outer braided layer with lower braid density provides axial strength for force transmission, while the inner braided layer with higher braid density provides flexibility for navigation. This composite approach allows both properties to coexist without compromise.
Solution Approach 2:
The catheter wall is segmented into functional layers with the outer layer dedicated to axial strength and the inner layer dedicated to flexibility. This segmentation allows each layer to optimize its specific function without interfering with the other, resolving the contradiction between axial strength and navigational flexibility.
4Strength
If the delivery catheter has high torsional strength to withstand rotation about its longitudinal axis, then the torque transmission capability is improved, but the flexibility to navigate tortuous vasculature is reduced
Solution Approach 1:
The catheter uses a composite braided structure where the outer braided layer with lower braid density provides torsional strength for torque transmission during steering, while the inner braided layer with higher braid density provides flexibility for navigation through tortuous anatomy. This resolves the contradiction between torsional strength and navigational flexibility.
Solution Approach 2:
The catheter structure is segmented into an outer layer optimized for torsional strength and an inner layer optimized for flexibility. This functional segmentation allows the catheter to transmit torque effectively for steering while remaining flexible enough to navigate complex vascular pathways.
Data Source
AI summary
A system for delivering an implantable medical device to an implant location includes a control handle portion, a catheter portion coupled to the control handle portion, and a distal portion configured to receive the implantable medical device. The catheter portion includes outer shaft including an inner braided layer extending axially along the outer shaft, an outer braided layer extending axially along the outer shaft, wherein the outer braided layer has a lower density of braids relative to the inner braided layer, and an axial spine positioned between the inner braided layer and the outer braided layer extending axially along the outer shaft.