Nitinol Guidewire Pigtail Tip Kinking
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Solution Overview
Problem
Traditional stainless steel guidewires used in cardiac procedures are prone to kinking and deformation due to deflection forces, posing risks of damage to heart tissues and prolonging procedure times, as they often require replacement and can dislodge plaque, increasing the risk of stroke.
Innovation Solution
A guidewire with an elongated core made of superelastic nitinol material, featuring a tapered section and a pigtail-shaped atraumatic tip, optionally coated with a polymeric sleeve for reduced friction and a radiopaque coil to manage bending stiffness, designed to navigate through the heart's vasculature without kinking or causing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If stainless steel guidewires are used to provide rigidity and steerability, then the guidewire can maintain structural integrity, but the guidewire becomes susceptible to kinking and plastic deformation due to deflection forces
Solution Approach 1:
The guidewire changes the material parameter from traditional stainless steel to a composite structure with a soft flexible core and a stiffening layer. This parameter change allows the guidewire to maintain structural integrity while resisting kinking and plastic deformation through the combined properties of the layered construction.
Solution Approach 2:
The guidewire employs a composite material structure consisting of a soft flexible core (such as polymer or elastomer) combined with a stiffening layer (such as braided wire mesh or memory alloy). This composite construction provides both the flexibility needed to navigate vasculature and the rigidity to resist deflection forces without kinking.
2Reliability
If the guidewire is pulled back into the catheter to avoid plastic deformation, then deformation is prevented, but the procedure time is prolonged and the guidewire may become locked in the catheter
Solution Approach 1:
The guidewire incorporates a stiffening layer and superelastic materials that provide beforehand protection against plastic deformation. This prior cushioning allows the guidewire to withstand deflection forces during the procedure without deforming, eliminating the need to pull it back into the catheter and avoiding procedure delays.
3Ease of operation
If the guidewire is passed through the aortic valve and carotid arteries to provide a predetermined track, then catheter positioning is improved, but the risk of plaque dislodgement and stroke increases
Solution Approach 1:
The guidewire changes the tip geometry parameter to include a pigtail configuration and radiopaque markers. The pigtail shape provides atraumatic engagement with the aortic valve and carotid arteries, reducing plaque dislodgement risk while maintaining the ability to establish a predetermined track for catheter positioning.
4Adaptability or versatility
If the guidewire uses tight bending radii to navigate the heart, then access to target locations is improved, but the guidewire may plastically deform due to the small bending radii
Solution Approach 1:
The composite construction with soft flexible core and stiffening layer allows the guidewire to navigate tight bending radii in the heart without plastic deformation. The soft core provides flexibility for navigation while the stiffening layer maintains structural integrity during tight deflections.
Solution Approach 2:
The guidewire incorporates superelastic materials that change the mechanical response parameter to allow reversible elastic deformation at tight bending radii. This parameter change enables the guidewire to accommodate small bending radii in cardiac anatomy without permanent deformation.
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 nitinol guidewire maintains flexibility and avoids kinking, reducing the risk of procedural complications such as heart wall perforation and stroke, allowing for safer and more efficient cardiac interventions by maintaining guidewire integrity throughout the procedure.
Implementation Method 1
The elongated core may be made from a superelastic material, such as nitinol
Implementation Method 2
a radiopaque coil to manage bending stiffness
Data Source
AI summary
A delivery guidewire for navigating a catheter in the heart to deliver a valve prosthesis. The delivery guidewire comprising an elongated core, an outer sleeve disposed on the elongated core, and a coil disposed on a distal portion of the elongated core. The delivery guidewire having a first section having a generally uniform diameter and a second section having a tapering section. A distal portion of the second section of the delivery guidewire comprises a pigtail shape atraumatic tip which can remain in the left ventricle.