Patent ID: 7241286

Claim:
A flush catheter configured to be introduced into a lumen to create an optically transparent flush zone, comprising: a catheter body having a non-occlusive distal end configured to be introduced into a lumen and an inner cavity, the inner cavity being configured to communicate with a proximal source of flush solution and expel the flush solution at a distal end of the catheter; an image probe assembly contained within the catheter body; one or more openings provided in the catheter body configured to expel therethrough flush solution; a sheath at least partially covering the one or more openings, wherein a circumferential gap exists between the sheath and a catheter body, wherein when flush solution is expelled through the one or more openings into the gap, the flush solution is directed by the sheath to flow along an outer surface of the catheter body toward a proximal end of the catheter body, and wherein a flush solution flow rate and the gap are configured such that a volume flow rate of the expelled flush solution is substantially equivalent but opposite to that of locally flowing blood thereby creating the optically transparent flush zone along a length of the outer surface of the catheter body between the outer surface of the catheter body and an inner surface of the lumen such that non-occlusive optical imaging of the lumen can be performed by the image probe assembly.