Monolithic Guidewire Diameter Profiling to Prevent Kinking

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Solution Overview

Problem

Existing guidewires face issues with undesirable welds or braze joints that can lead to kinking or fracture, and discrete diameter gradients that introduce stress and cracking, necessitating a method to create a guidewire with varying flexibility and torsional stiffness without these drawbacks.

Innovation Solution

A method involving cold work through processes like rolling, drawing, or swaging to create a guidewire with a distal section that is more flexible and shapeable, while maintaining high torque, by reducing the inner and outer diameters of the distal section and ensuring a uniform diameter along the guidewire, without the need for welding or joints, using centerless grinding and laser-cut coils for enhanced flexibility and torque.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If welds or braze joints are used to join guidewire sections, then the guidewire can be assembled from multiple components, but the guidewire becomes susceptible to kinking or fracture at the joints

Engineering Contradiction:

Improveassembly of guidewire componentsVSAvoidresistance to kinking and fracture

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent merges multiple guidewire sections into a single monolithic structure through continuous drawing and cold working processes, eliminating the need for welds or braze joints. This integration ensures uniform material properties and eliminates weak points where kinking or fracture could occur, while still allowing variation in diameter along the length of the guidewire to achieve different flexibility characteristics in different sections.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent creates functional segmentation within a continuous structure by varying the diameter of different sections through controlled cold working. The distal section has a smaller diameter for flexibility, while the proximal section has a larger diameter for torque transmission, all within a single uninterrupted guidewire structure that avoids joints.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If discrete diameter gradients are applied to the guidewire, then flexibility varies along the length, but stress concentrations and cracking occur at the gradient transitions

Engineering Contradiction:

Improvevarying flexibility along guidewire lengthVSAvoidresistance to stress and cracking

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent continuously changes the diameter parameter along the length of the guidewire through progressive cold working processes. Instead of discrete steps, the diameter transitions smoothly from the distal to proximal end, eliminating stress concentrations at abrupt transitions while maintaining the desired variation in flexibility and torsional stiffness along the guidewire length.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If the entire guidewire is made of formable material like stainless steel, then the guidewire can be shaped by the physician, but the proximal end lacks sufficient torsional stiffness

Engineering Contradiction:

Improveformability of guidewireVSAvoidtorsional stiffness

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The patent applies local quality by giving different sections of the guidewire different diameters to optimize their functions. The distal section has a smaller diameter for flexibility and formability, allowing the physician to shape it as needed. The proximal section has a larger diameter providing sufficient torsional stiffness for force transmission, while the entire structure remains monolithic for reliable performance.

Inventive Principle:

Principle #3Local quality

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 method allows for a guidewire with a malleable distal tip that can be shaped as needed, providing high flexibility and torque for navigating tortuous vessels without the risks of cracking or kinking, while eliminating the need for welding and reducing stress points.

Implementation Method 1

applying cold work to the elongated tubular member through a process including any of rolling, drawing or swaging in a sequence that comprises reducing the elongated tubular member inner diameter and outer diameter

Methodology Applied

Scientific EffectCold work: Cold-forming

Implementation Method 2

A reducing process is then applied to the elongated tubular member to reduce the elongated tubular member to have a constant outer diameter over the first length and the second length

Methodology Applied

Scientific EffectGrinding: Abrasion

Data Source

PatentUS11684759B2Guidewire having varying diameters and method of making

Publication Date: 2023.06.27 ABBOTT CARDIOVASCULAR SYSTEMS INC

AI summary

A method of making a medical guidewire including providing a wire having a length that includes a proximal length and a distal length. The method further includes applying cold work to the distal length and not applying cold work to the proximal length, thereby imparting to the distal length a diameter that is smaller than the proximal length diameter; and applying a reducing process to the wire whereby the proximal length is reduced to have an outer diameter that is the same as the outer diameter of the distal length. The proximal length has an inner diameter and the distal length has an inner diameter that is less than the inner diameter of the proximal length.