Guidewire stiffness: what's in a name?

Area of Science:

• Biomedical Engineering
• Medical Device Technology

Background:

• Endovascular procedures rely on guidewires with specific stiffness properties.
• Current stiffness descriptors for guidewires are often vague and lack objective measurement.

Purpose of the Study:

• To quantify the bending stiffness of commonly used guidewires.
• To determine the flexural modulus of various guidewires as an objective measure of stiffness.

Main Methods:

• Eleven different stiff guidewires were tested using a 3-point bending test on a tensile testing machine.
• Flexural modulus was calculated in gigapascals (GPa) from bending test data.
• Testing was conducted on multiple specimens at various points along the guidewire length.

Main Results:

• Flexural modulus varied significantly across different guidewire types and brands.
• Some guidewires labeled "extra stiff" exhibited a five-fold difference in flexural modulus.
• Measured flexural modulus ranged from 9.5 GPa to 158.4 GPa.

Conclusions:

• Stiffness descriptors like "stiff" or "extra stiff" have poor correlation with measured flexural modulus.
• Recommend including flexural modulus on guidewire packaging and in device instructions for use.
• Standardizing stiffness measurement is crucial for accurate medical device selection and procedural safety.