Wire guides are elongate flexible members used to provide a path along which another medical device can be moved. The path provided by the wire guide can be used to navigate another medical device, such as a catheter through a body vessel. The use of wire guides to define such a path is known in the art. Briefly, a wire guide is navigated through a body lumen toward a point of treatment. Once positioned within the lumen, a therapeutic or diagnostic device, (i.e., a catheter) may be advanced over the wire guide to the target site and the desired therapeutic or diagnostic steps may be performed. The wire guide provides an established path for placing other devices and eliminates the need for performing delicate navigation procedures for each device passed into the body lumen, for example when additional procedures are performed. In some procedures, it is desirable to be able to withdraw the wire guide back through the catheter.
During placement of the wire guide, an operator must navigate the wire guide through a tortuous pathway in the body lumen due to the presence of natural bends and/or curves, or unnatural impediments, such as tumors, build-ups, and/or strictures. The presence of a tortuous path may make navigation of a wire guide through the path difficult, for example, the tip of the wire guide may get bent away from the desired path or caught in a stricture, or in some cases even perforate the wall of the lumen, etc. making further navigation into the lumen difficult or impossible.
The art contains many examples of wire guides having straight, flexible tips intended to aid in navigation of tortuous body lumens. The presence of a straight tip that is advanced tip forward, however, may make navigation more difficult. For example, upon encountering an impediment, the advancing tip may bend (reflex) into the lumen wall and become caught. Contact of the advancing tip with the lumen wall may prevent the wire guide from advancing further into the lumen as well as possibly damaging the lumen wall.
What is needed is a device for positioning a wire guide for navigating a tortuous body lumen and which addresses the other deficiencies described above, but which is still readily retractable into a catheter.