Catheter

Overview

Catheters are shaped and sized for the task and the anatomy. Diagnostic (selective) catheters are used mainly to deliver contrast for angiography; guide catheters are larger and stiffer, providing a stable platform to support smaller devices advanced through them; and microcatheters are very small, flexible, coaxial catheters used to reach distal or tortuous targets beyond where a standard catheter can safely go. Shape is chosen to help the catheter engage a specific vessel origin or navigate a specific anatomical course.

Sizing and compatibility

• Like sheaths, most catheters are sized on the French scale, describing outer diameter; microcatheters are often instead described by inner lumen diameter, since their small size is chosen to fit through a standard catheter or sheath.
• As with every other device in this guide, compatibility — not the number alone — is what the supervising operator checks before a catheter is chosen and advanced.