Characteristics of a diagnostic catheter
Catheters may be selected for a specific application based on many characteristics. Although there are numerous catheters, experience and personal preference play a large role in the selection process.
- • Length: Catheters are available in various lengths, the most common being 65 cm and 100 cm. The appropriate length is based on the access site and desired application. From a femoral approach, a 100-cm-long catheter may be used for a cerebral arteriogram, whereas a 65-cm-long catheter would suffice for a renal arteriogram.
- • Tip configuration: Tip configuration describes the curve on the leading edge of the catheter. Various curves are available that are designed to select branch vessels that originate at different angles. Common catheter curves include Cobra, Simmons, and Berenstein.
- • Outer diameter: Most diagnostic catheters used today are 4 or 5 French (Fr), meaning that they are less than 2 mm in diameter.
- • Inner diameter: This describes the inner channel of the catheter. Most catheters are designed to accommodate guidewires that are either 0.035 inches or 0.038 inches in diameter. It is important to match the inner diameter of the catheter with the devices (wire or coil) that are placed through it.
- • Coating: Some catheters have a hydrophilic coating that becomes very slippery when wet. This may facilitate crossing a stenosis.
- • Stiffness: Some catheters may contain braided fibers within the shaft. Braiding of polymers increases the stiffness of the catheter. Some clinical applications are better suited to stiffer catheters, whereas others are better served by floppier ones.