Guidewire core

The core of a coronary guidewire determines many of the performance characteristics of the device. The core of a coronary guidewire is usually ground to a taper towards the end and this is where the tip attaches to the core. If guidewire core starts tapering more towards the tip, the coronary guidewire as a whole becomes more rigid, steerable and torquable. The opposite happens when the core other coronary guidewire tapers more proximally allowing for a longer tip and a more flexible tip. The core may be either continuous or joined. If the core is joined then it is more likely to bend or prolapse when the guidewire is advanced. Coronary guidewire cores that are made of stainless steel are stiffer, provide greater support, and provide greater torque control. In contrast, coronary guidewire cores that are made of nitinol are much more flexible.

The guidewire core can be composed of either nitinol, stainless steel or a similar metal.

Shown below is the structure of a guidewire with a nitinol core:

• Super-elastic alloy designed for kink resistance
• Excellent flexibility and steering
• Probably more durable in nature
• Better trackability
• Reduced prolapse

• A nitinol guidewire may be less torquable
• A nitinol guidewire core may store torque without necessarily transmitting the torque to the tip
• Wires with single nitinol cores sometimes “wind up” and store the torque

• As a result of their flexibility and durability, coronary guidewires with a nitinol core are more likely to enter a retroflexed circumflex coronary artery.

Stainless steel was the original core material used in coronary guidewires. Shown below is the structure of a stainless steel guidewire core (Courtesy of Abbott Vascular)

• The stainless steel core provides greater pushability, support, torquability, and good shapeability in “core-to-tip” wires.

• Tendency to kink
• Less flexible than newer core materials

Shown below is the structure of a high tensile strength stainless steel guidewire core:

• More durable than regular stainless steel
• Retains shape more
• Improved flexibility
• Improved steering and tracking

Shown below is the structure of a Asahi Tru Torque Steel guidewire core: