A transparent plastic collapsible balloon is attached to the distal end of a flexible bronchoscope or angioscope. The inflatable balloon has a cavity or "working well" at its distal end which communicates by means of a tube with the central channel of the angioscope. Separate channels of the angioscope allow inflation of the balloon after it has been introduced into a vein or artery and visualization of tissue against which the distal end of the balloon is pressed. A laser fiber, forceps, or other instrument can be passed through the central channel of the angioscope, and through an opening in the distal end of the balloon into the working well cavity to allow lasing or other procedures to be performed on tissue abutted by the balloon and isolated by the working well cavity, and to also allow direct visualization of such procedures. Accurate visualization of the operation of lasing, use of the forceps to obtain biopsies or to remove foreign objects, and other intravascular procedures can thereby be achieved.