Features

This is a self expanding nitinol stent that can be used in either the biliary system or vascular system. Cook claim good radial force, flexibility and durability (as do all manufacturers). There are two versions, the 635 that goes over a 0.035 inch diameter guide wire and the 518 that accepts a 0.018 inch diameter guide wire. The following refers to the 635 version.

Design/construction

The stent has gold markers on each end to aid visibility and placement and comes premounted on a 6F introducer. The stent can be placed through a 6F sheath and takes a standard 0.035 inch guidewire. The stent is MRI compatible.

In use

The stent can be inserted through a 6F sheath. Stent positioning is aided by 4 highly radio opaque gold markers on each end. Deployment is fairly standard with a safety lock removed first. Then hold the central metal cannula in place relative to the patient and uncover the stent by withdrawing the handle. The stent cannot be recovered during deployment.

Results so far

So far we have had excellent results with this stent in more than 20 patients. Its fairly wide mesh allows for placement in a T configuration for hilar tumours. The disadvantage of this may be earlier tumour ingrowth ?

Conclusion

Simple to deploy and it seems to have relatively good radial force. The wider mesh allows insertion in a T configuration. The end markers aid positioning. I have yet to try the 518 version and am keen to hear from anyone who has !

For:

• Rapid easy deployment
• Flexible
• Opaque end markers

Against:

• 6F sheath needed for 635 version
• Not very visible

Dr Phil Haslam
Consultant Radiologist