Twisted Vascular Coil for Irregular Aneurysm Filling
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Solution Overview
Problem
Conventional primary wind coils lack flexibility and packing density, making them inadequate for filling complex or irregularly shaped vascular cavities like aneurysms, and they do not easily adapt to varying anatomical shapes during deployment.
Innovation Solution
A flexible metal wire coil with a twisted pattern is formed using a mandrel with a non-circular cross-section that twists along its axis, allowing for a variable bending moment and improved filling capabilities, enabling the coil to conform to complex shapes and provide better occlusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a conventional primary wind coil with constant diameter cylindrical mandrel is used, then the coil has uniform bending stiffness in all directions, but the coil lacks flexibility and packing density for complex vascular cavity shapes
Solution Approach 1:
The patent applies asymmetry by using a mandrel with non-circular cross-section (oval, triangular, or other asymmetric shapes) instead of a constant diameter cylindrical mandrel. This creates a primary coil with non-uniform bending stiffness that varies around the circumference, allowing the coil to be more flexible in certain directions while maintaining stability in others, thereby enabling better adaptation to complex vascular cavity shapes
Solution Approach 2:
The patent implements local quality by creating regions of different bending stiffness within the same coil structure through the non-circular mandrel design. Different portions of the coil cross-section have different stiffness characteristics, allowing localized flexibility in specific directions while maintaining overall structural integrity, thus improving packing density and conformability to irregular aneurysm shapes
2Device complexity
If a conventional primary wind coil with constant diameter is used, then the coil has simple structure, but the coil cannot achieve variable stiffness for filling aneurysms of various sizes and shapes
Solution Approach 1:
The patent uses asymmetric mandrel cross-sections to create coils with variable stiffness characteristics without adding complex multi-component structures. The non-circular geometry inherently produces different bending moments in different planes, achieving variable stiffness through geometric asymmetry rather than structural complexity
Solution Approach 2:
The patent changes the geometric parameters of the mandrel (cross-sectional shape, dimensions, and orientation) to control the bending stiffness of the resulting coil. By varying the mandrel's non-circular cross-section parameters, the coil achieves different stiffness characteristics in different directions, enabling adaptation to various aneurysm sizes and shapes while maintaining a relatively simple single-structure design
3Stability of the object's composition
If a conventional primary wind coil is used, then the coil has constant bending moment about the longitudinal axis, but the coil cannot completely fill irregularly shaped vascular cavities
Solution Approach 1:
The patent employs asymmetric mandrel cross-sections that create non-uniform bending moments around the coil circumference. This asymmetry allows the coil to pack more efficiently into irregular vascular cavities by having flexible regions that can conform to cavity walls while maintaining sufficient stiffness for structural support, thereby increasing effective packing density
Solution Approach 2:
The patent creates local variations in bending moment characteristics through the non-circular mandrel design. Different angular positions around the coil have different stiffness properties, enabling the coil to locally adapt to the irregular geometry of vascular cavities and achieve more complete filling compared to uniform coils
Data Source
Figure 1A~3A
Figure 3B~4
Figure 5~10
AI summary
A flexible metal wire coil is formed with a twisted coil pattern, by forming a primary coil on a special mandrel formed from two or more strands of material twisted helically about a longitudinal axis to have a helical shape. The primary coil wire is wound around the mandrel to give the primary coil a twisted shape corresponding to the helical shape of the mandrel.