Guide wire assembly

Abstract

Systems and methods for guiding the advancement of a guide wire through body tissue are described. In one embodiment, the guide wire has a first end, a second end, or guide wire head, a bore extending between the first and second ends, and includes an interferometric guidance system. The interferometric guidance system includes a low coherent illumination source, an optical beam splitter, a first optic fiber, a second optic fiber, and a photodetector. Each optic fiber includes a first end and a second end, and is wrapped around a piezo electric transducer (PZT). The second optic fiber has a fixed reflector on the second end. The photodetector is configured to determine interference between a first reflected light beam propagating through the first optic fiber and a second reflected light beam propagating through the second optic fiber. In one embodiment, the guide wire second end is inserted into a blood vessel so that the first optic fiber second end is inserted in the vessel. The beam splitter splits a light beam from the illumination source into two beams which propagate separately along the first optic fiber and the second optic fiber. The beams are reflected from the optic fiber second ends, and are recombined at the beam splitter. Before advancing the guide wire further, sawtooth voltage signals are applied to the PZTs, causing the PZTs to alternately expand to contract and change the optical path length along the two optic fibers. The reflected light beams interfere constructively or destructively depending on their respective optical path lengths. By enabling the PZTs, various interferences are generated by changing the optical path lengths along the first and second optic fibers. The interference information is then processed to determine the safety of advancing the guide wire further into the blood vessel.