Braided Stent Sizing via Segmented Foreshortening Prediction
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Solution Overview
Problem
The foreshortening behavior of dense mesh braided stents makes it difficult to accurately predict their length after implantation in blood vessels, increasing surgical risk and reliance on experience for effective selection and placement.
Innovation Solution
A sizing method that involves obtaining geometric models of aneurysms and parent arteries, determining the expected landing zone, and discretizing the working zone into segments to calculate the required braided stent length and diameter, using equations to simulate implantation and select a suitable stent based on these dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dense mesh braided stents are used to occlude aneurysms, then occlusion effectiveness is improved, but length prediction accuracy deteriorates due to foreshortening behavior
Solution Approach 1:
The stent is divided into multiple discrete segments along its length, with each segment's foreshortening behavior calculated independently based on local diameter and braiding parameters. This segmentation allows accurate prediction of total stent length by summing individual segment contributions, resolving the length prediction inaccuracy caused by uniform foreshortening assumptions.
Solution Approach 2:
The method calculates foreshortening ratio locally for each stent segment based on its specific diameter and braiding characteristics, rather than applying a uniform foreshortening ratio to the entire stent. This local quality approach accounts for variations in stent geometry and braiding density, improving length prediction accuracy while maintaining occlusion effectiveness in critical regions.
2Reliability
If non-uniform braided stent mesh is used to ensure aneurysm occlusion, then occlusion effectiveness is improved, but length prediction difficulty increases due to non-uniform foreshortening behavior
Solution Approach 1:
The non-uniform stent is segmented into discrete sections, with each segment's foreshortening behavior calculated independently based on local parameters. This segmentation transforms the complex non-uniform foreshortening problem into a series of simpler local calculations, reducing overall prediction complexity while maintaining accuracy for non-uniform mesh configurations.
Solution Approach 2:
The method uses parameter equations that relate stent diameter, wire diameter, braid angle, and mesh density to foreshortening ratio. By inputting local parameter values for each segment, the system automatically adjusts calculations to account for non-uniform mesh characteristics, simplifying the prediction process for complex stent geometries.
3Adaptability or versatility
If experience-based stent selection is used, then surgical flexibility is maintained, but surgical risk increases due to lack of reference for stent selection
Solution Approach 1:
The system performs preliminary calculations of stent foreshortening and implantation length before surgery, providing surgeons with reference data on expected stent behavior. This preliminary action includes calculating the relationship between nominal stent length and implanted length, allowing surgeons to select appropriate stent sizes with confidence while maintaining surgical flexibility.
Solution Approach 2:
The method provides feedback to surgeons by calculating and displaying the expected foreshortening ratio and implanted length based on selected stent parameters. This feedback loop allows surgeons to adjust their selection based on quantitative predictions, reducing surgical risk while maintaining the flexibility to adapt to specific patient anatomy and surgical conditions.
Data Source
AI summary
This application relates to a sizing method and computer equipment for braided stents. The sizing method includes: obtaining geometric models of aneurysm and parent artery, determining the expected landing zone of the braided stent, obtaining the centerline and cross-section of the blood vessel at the expected landing zone; obtaining the proposed diameter of the braided stent, thereby obtaining the first braided stent that meets the expectations, obtaining the anchoring section length of the first braided stent, obtaining the working zone length; discretizing the working zone into a finite number of discrete segments, obtaining the corresponding relationship between the length and diameter of the discrete segments, obtaining the diameter of the discrete segments, obtaining the length of the discrete segments based on the corresponding relationship and accumulating them until the total length equates the working zone length, obtaining the number of discrete segments.