Optically transparent fluids were investigated as a means of transmitting laser energy (LE) in laser angioplasty catheters as an alternative to fused silica fibers. A catheter was constructed which transmists LE through a flowing stream of iodinated contrast media. LE is launched into a stream of contrast media and is internally reflected by a lower index of refraction cladding --- providing transmission efficiency of 75%. As the stream exits the catheter, blood acts as an optical cladding and allows transmission 1 cm distal to the catheter tip. The low pressure stream removes intervening blood and provides an atraumatic surface for light interaction with target tissues. Fluoroscopy of the contrast stream allows real-time visualization of the catheter, the site of LE delivery and distal vasulature. We conclude that a fluid-core laser angioplasty catheter can transmit high peak-power laser energy and offers simplicity, blood removal, improved flexibiblity and real-time imaging during intravascular LE delivery.
K. W. Gregory and R. R. Anderson. Fluid-core optical transmission for laser angioplasty. In A. Katzir, editor, SPIE Proceedings of Optical Fibers in Medicine V, volume 1201, pages 156-161. 1990.