Segmented metallic guidewires
Inventors
Kocaturk, Ozgur • BASAR, Burcu • Lederman, Robert J.
Assignees
US Department of Health and Human Services
Publication Number
US-10695540-B2
Publication Date
2020-06-30
Expiration Date
2035-10-19
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Abstract
Disclosed herein are embodiments of segmented metallic guidewires that are suitable for MRI catheterization. Disclosed guidewires comprise a plurality of short conductive metallic segments that individually are short enough such that they do not resonate during MRI. The conductive segments are electrically insulated from each other and mechanically coupled together end-to-end via connectors, such as stiffness matched connectors, to provide a sufficiently long, strong, and flexible guidewire for catheterization that is non-resonant during MRI.
Core Innovation
Disclosed herein are embodiments of segmented metallic guidewires that comprise a plurality of short conductive metallic segments electrically insulated from each other and mechanically coupled together end-to-end via connectors. These conductive segments are individually short enough so they do not resonate during MRI, preventing standing wave formation. The connectors can be stiffness matched to the rods to provide a sufficiently long, strong, and flexible guidewire suitable for catheterization that is non-resonant during MRI procedures such as with 1.5T scanners.
The segmented metallic guidewires address the problem with conventional metallic guidewires, which are long conductors that resonate under MRI electromagnetic fields causing excess heating and vibration, making them unsafe for MRI-guided procedures. Non-metallic guidewires, while safe in MRI, often lack sufficient torquability and column strength, leading to mechanical failures. Hybrid designs have weaknesses at juncture points between components. The invention provides a segmented approach that preserves mechanical strength, flexibility, and torquability while avoiding resonance and heating during MRI.
The invention further includes features such as tubular or welded connectors that overlap insulated ends of metallic rods, with the rods commonly comprising materials like nitinol and connectors made of nitinol, titanium, or other MRI compatible metals. The insulation layers can be thermoset polymers surrounding the rods to electrically isolate segments. Additional outer polymeric layers or jackets provide mechanical strength, uniform diameter, and enhanced torque response. Stiffness matching between rods and connectors is used to achieve smooth flexion and enhanced column strength, preventing structural weaknesses at segment joints.
Claims Coverage
The patent includes three independent claims covering segmented metallic guidewires with electrically insulated metallic rods connected via metallic connectors, stiffness matching of rods and connectors, and specific configurations of connectors bonded and welded to rod ends.
Segmented guidewire construction with electrically insulated metallic rods and tubular connectors
A guidewire composed of multiple elongate metallic rods in axial end-to-end alignment with polymeric insulation layers separating adjacent rod ends. Tubular metallic connectors overlap the insulation layers and adjacent rod ends to secure rods together without electrical coupling. An outer polymeric layer surrounds the insulation layer and connectors to provide a uniform outer diameter.
Stiffness matched metallic rods and connectors with controlled connector length
The metallic rods and connectors are matched in stiffness, where connectors have an axial length shorter than the radius of curvature that causes plastic deformation of the rods. This ensures uniform flexibility and strength along the guidewire.
Connectors adhesively bonded and welded to insulated and uninsulated rod ends
Each connector has a first axial end adhesively bonded to an electrically insulated end portion of one metallic rod and a second axial end welded to an uninsulated end portion of another rod. The first end includes an annular rim with circumferential notches filled by a polymeric jacket, ensuring electrical insulation and mechanical security while maintaining a uniform outer diameter.
The claims collectively cover segmented metallic guidewires that employ short, electrically insulated metallic rods connected by stiffness matched connectors that secure the rods mechanically while preventing electrical resonance during MRI. Various connector configurations, bonding techniques, and insulation layers combine to provide MRI-safe, mechanically robust guidewires with uniform flexion and strength properties.
Stated Advantages
Prevention of resonance and undue heating during MRI procedures by using short electrically insulated metallic segments.
Stiffness matching between rods and connectors to provide smooth bending, increased column strength, and reduced risk of kinking or mechanical failure.
Uniform outer diameter providing enhanced torque control and mechanical flexibility with redundant insulation for clinical safety.
Improved navigation through tortuous anatomical structures due to enhanced flexibility and column strength.
Reduced risk of mechanical failure at segment junctions inherent in prior hybrid designs.
Safe use during MRI catheterization allowing radiation-free procedures with real-time MRI guidance.
Documented Applications
Use of segmented metallic guidewires during MRI catheterization procedures for navigating vascular and non-vascular structures.
Guidewire-based catheter navigation under MRI providing real-time imaging of devices and soft tissue.
Diagnostic and therapeutic medical device guidance including catheters, stents, cardiac occluder devices, bioptomes, and ablation devices.
Applications in MRI and other electromagnetic field environments where resonance and heating of metallic guidewires is a concern.
Use in microwave energy ablation procedures to avoid resonant device heating.
Applications involving magnetic attraction in minimally invasive procedures, for example, device docking across soft tissue structures.
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