ABSTRACT
Microcatheters are small, lengthy, and flexible catheters that are compatible with small caliber guidewires. They may be used for strategic angiography, to exchange guidewires, and to provide support for a guidewire system in a challenging situation. Microcatheters may also be used to provide therapy, such as when small caliber coils are delivered or therapeutic medication is administered. Thrombolytic agents may be delivered through microcatheters, for example. Microcatheters are generally 2.3 to 3.8 Fr in caliber, in comparison to the standard 5-Fr catheter used with a 0.035-in. system (Fig. 1).The tip of the catheter may be floppy or stiff and may be either straight or have angles at the tip. These catheters may be designed to accept a 0.10-in., a 0.014-in., or a 0.018-in. diameter guidewire. They are generally 120 to 150 cm in length but may be even longer. The longer and smaller caliber the catheter becomes, the more the friction increases during guidewire passage through the catheter and also during catheter passage over the guidewire. There are some microcatheters which have radio opaque tips, which make them more readily visible, and also some microcatheters that have stiff tips. The microcatheters with the stiff tips may be used for crossing occlusions. The catheter and the guidewire can be used in a hopscotch manner to get across
an occlusion, each providing support to the other. Microcatheters may be used to provide support to a guidewire system where support is inadequate due to the lack of strength of the guidewire shaft itself. The relationships of the guidewire to the surrounding tissues may be changed significantly by adding a microcatheter.
