Although laser thermal angioplasty (LTA) with a laser heated metal probe has been tolerated in diseased human coronary arteries, definition of a safety threshold is lacking. Determination of safer operation parameters for coronary LTA using a new “over the wire” 1.3‐mm laser probe catheter was attempted in seven normal pigs in which platelets were labeled with indium‐III. Argon laser power of 10 watts was used for 1, 2, 3, and 5 seconds. Macroscopic findings, platelet deposition and histologic changes were compared between the laser treated coronary segments and controls, the nonheated laser probe, and the wire alone segments. After 1‐second LTA, there was no vessel perforation or occlusive thrombi and only infrequent nonocclusive thrombi; platelet deposition was minimal; and histologic alterations rare and superficial. These findings were comparable to controls, the nonheated laser probe, and the wire alone segments. In contrast, vessels treated for 2, 3, and 5 seconds had more frequent perforation, and occlusive and nonocclusive thrombi that was accompanied by platelet deposition significantly greater than vessels treated with LTA for I second. A deep histologic injury was present in most of these segments. Additionally, the safety of laser delivery of I second repeated for five times was tested in two additional pigs. On macroscopic and histologic analysis the incidence of vessel perforation, occlusive and nonocclusive thrombi appeared slightly less when compared to the 2‐, 3‐, and 5‐second LTA groups, and more than the 1‐second LTA group. Platelet deposition was lower than the 2‐, 3‐, and 5‐second LTA groups, and higher than the 1‐second pulse group. Thus, 1‐second pulses are the threshold for safe application of LTA in normal swine coronary arteries. LTA for longer periods of energy delivery is accompanied by significant platelet deposition and high rates of thrombi formation focclusive and nonocclusive) and vessel wall perforation. Repetitive short 1‐second periods of laser energy delivery do produce an accumulative injury but to a less extent than single pulses. This mode of laser energy delivery could possibly improve the safety for human LTA.
|Number of pages||9|
|Journal||Journal of Interventional Cardiology|
|State||Published - Sep 1991|