Patent ID: 8221310

Claim:
A method of treating a tissue region within a body lumen, comprising: positioning an open area of a barrier or membrane projecting distally from a deployment catheter against or adjacent to the tissue region to be treated, wherein the barrier or membrane self-expands into an expanded deployed configuration, and where the barrier or membrane comprises a non-inflatable membrane which defines the open area therein which is in fluid communication with a lumen defined through the catheter and also with an environment external to the barrier or membrane through an opening defined by the barrier or membrane; displacing an opaque fluid with a transparent fluid from the open area defined by the barrier or membrane and the tissue region by infusing one or more streams of the transparent fluid into the open area in a spiral manner such that the opaque fluid is displaced from within the open area and through the opening into the environment external to the barrier or membrane; and visualizing the tissue region within the open area through the transparent fluid.