MRI-Compatible Transseptal Needle With Polymer Shaft and Anti-Skiving Bevel
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Solution Overview
Problem
Current transseptal needles are not compatible with MRI-guided procedures due to RF heating concerns and pose a risk of dilator lumen skiving, leading to particulate generation.
Innovation Solution
A needle catheter designed with a polymeric shaft and a non-ferrous metal tip, featuring a multi-angle bevel and anti-skiving measures, including a strain relief and outer collar, to ensure MRI compatibility and reduce particulate generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If stainless steel is used for the needle catheter shaft to provide rigidity for transseptal crossing, then the needle maintains sufficient stiffness to deliver force from handle to tip, but the needle becomes incompatible with MRI-guided procedures due to RF heating concerns
Solution Approach 1:
The needle catheter employs a composite construction with a polymeric shaft (MRI-compatible, RF-heating resistant) and a non-ferrous metal tip (nitinol or stainless steel, providing the necessary rigidity and puncturing capability). This composite design allows the shaft to be made of MRI-safe material while the tip maintains the mechanical properties needed for effective transseptal crossing, thereby resolving the contradiction between rigidity and MRI compatibility.
Solution Approach 2:
Different portions of the needle catheter are made from materials with different properties: the shaft is made of polymeric material for MRI compatibility and RF safety, while the tip is made of non-ferrous metal for rigidity and puncturing function. This local differentiation allows each part to have the optimal material properties for its specific function, resolving the contradiction between overall rigidity and MRI compatibility.
2Ease of operation
If a sharp beveled needle tip is used to facilitate easy puncturing of the septum, then the needle can penetrate tissue with less force, but the needle point may scrape the wall of the dilator lumen and generate particulate matter
Solution Approach 1:
The needle tip features an asymmetric multi-angle bevel configuration where the bevel angles are not uniform around the tip. Specifically, the leading edge bevel angle is different from the trailing edge bevel angle, with the leading edge having a smaller angle for easier tissue penetration. This asymmetric design facilitates easy puncturing while the geometric configuration helps direct the needle point away from the dilator lumen wall, reducing skiving and particulate generation.
Solution Approach 2:
The needle tip design incorporates a variable angle bevel that transitions along the length of the tip, creating a three-dimensional geometric profile. The bevel angle varies from the proximal to distal end of the tip, with the sharpest angle at the very tip for penetration and progressively shallower angles toward the base. This dimensional variation in the bevel geometry enables easy puncturing while maintaining clearance from the dilator lumen wall throughout the insertion path.
3Object-affected harmful factors
If the needle tip is made of non-ferrous metal material to ensure MRI compatibility, then RF heating is minimized, but the needle may still pose skiving risks during introduction through the dilator
Solution Approach 1:
The needle catheter uses a composite design where the shaft is polymeric (MRI-compatible) and the tip is non-ferrous metal (nitinol or stainless steel). The non-ferrous metal tip provides the necessary rigidity and puncturing capability while being MRI-compatible (non-ferrous), thus eliminating RF heating concerns. The anti-skiving geometric features are integrated into this composite structure to prevent dilator lumen skiving during insertion.
Data Source
AI summary
A needle catheter that comprises: a handle; a shaft formed of a polymeric material and having a proximal end coupled to the handle; a needle tip formed of a non-ferrous metal material and comprising a tube with (i) a proximal end coupled to a distal end of the shaft, and (ii) a distal end with a multi-angle bevel defining a pointed structure with a side profile having a variable angle with respect to a center axis of the needle tip; and a central lumen extending through the handle, the shaft and the needle tip.