Controlled Endoprosthesis Balloon Expansion With Yield-Threshold Cover
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Endoprostheses experience uneven expansion during deployment due to variable resistance, leading to undesirable foreshortening and interference between stent elements, particularly with larger diameter stents.
Innovation Solution
A balloon expandable endoprosthesis system featuring a cover over the balloon that maintains an intermediate diameter until the inflation pressure exceeds the yield strength of the cover, mitigating uneven expansion and preventing foreshortening by limiting the angle between stent elements to no more than 35 degrees.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a balloon is used to expand the endoprosthesis, then the endoprosthesis can be deployed from undeployed to deployed state, but uneven expansion occurs due to variable resistance along the endoprosthesis length
Solution Approach 1:
The balloon is divided into multiple segments with different expansion characteristics. Each segment corresponds to a region of the endoprosthesis and provides controlled expansion force to compensate for variable resistance, ensuring uniform expansion throughout the device.
Solution Approach 2:
Different portions of the balloon are designed with different mechanical properties and expansion characteristics tailored to the specific resistance characteristics of corresponding endoprosthesis regions, providing localized control over expansion forces.
2Productivity
If the balloon expands rapidly to achieve deployed diameter quickly, then deployment time is reduced, but foreshortening of the endoprosthesis occurs
Solution Approach 1:
The balloon is pre-formed with a configuration that maintains a substantially constant diameter during expansion. This preliminary structural preparation ensures that as the balloon inflates, it expands radially rather than longitudinally, preventing foreshortening while maintaining rapid deployment.
Solution Approach 2:
The balloon's geometric parameters are specifically designed to maintain constant diameter during expansion. By controlling the relationship between balloon length, diameter, and material properties, the system achieves rapid expansion without compromising endoprosthesis length.
3Ease of operation
If the balloon is made compliant to facilitate expansion, then easier deployment is achieved, but the balloon cannot maintain constant diameter during expansion
Solution Approach 1:
The balloon is constructed as a composite structure combining compliant materials that facilitate easy expansion with structural elements that maintain constant diameter. This composite design allows the balloon to be both easy to deploy and geometrically stable during expansion.
Solution Approach 2:
The balloon utilizes curved and geometric configurations that inherently maintain constant diameter during expansion. The curved structure of the balloon, when inflated, naturally distributes stress to maintain circular cross-section and constant diameter throughout the expansion process.
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
The system ensures even expansion of the endoprosthesis, preventing foreshortening and maintaining the structural integrity of the stent by controlling the expansion process, thereby ensuring proper deployment without interference between stent elements.
Implementation Method 1
maintained at about the intermediate diameter until the inflation pressure increases by at least 1 atmosphere to overcome a yield strength of the cover
Data Source
AI summary
A medical assembly includes a balloon expandable endoprosthesis comprising a plurality of ringed stent elements flexibly connected to each other via at least one flexible connector, the endoprosthesis being deployable from an undeployed state with an undeployed diameter to a deployed state with a deployed diameter. The medical assembly further includes a catheter assembly comprising a balloon, and a cover along the balloon. The endoprosthesis is coaxially located about the balloon and the cover. One or more portions of the balloon and the cover reach an intermediate diameter between the undeployed diameter and the deployed diameter in which the portions of the balloon and the cover are inflated by increasing an inflation pressure within the balloon and approximately maintained at about the intermediate diameter until the inflation pressure increases by at least 1 atmosphere to overcome a yield strength of the cover.