Finally, the radiopaque metal must adhere without the possibility of peeling or delamination. Catheters, and especially stents, are severely flexed, and the bond between the metal and the device must be able to withstand the forces generated. Whether the device is indwelling or transcutaneous, poor coating adhesion can result in serious complications. An early method of marking catheters involved crimping or swaging metal bands at selected points so that the practitioner could see the location of the device. Catheters with bands of gold and other noble metals are still being marketed, but cardiologists generally prefer the newer methods of marking.
Bands have the potential for coming loose and shifting or falling off.
They have also been known to actually cause an abrasion to the intima during insertion of the catheter. Additionally, cellular debris can become trapped between the device and the band, and the edges of the band can serve as a site for thrombus formation. Another means of achieving visibility is by loading the catheter material with a metal powder. A metallic element long employed in radiology, barium is most often used, although tungsten and other fillers are appearing on the market. A distinct disadvantage of these types of filled catheters is that the entire length of the device is opaque, which prevents viewing of the vein or artery wall behind the catheter.