<title>Laser irradiation reduces vasoreactivity of coronary artery: implication for prevention of coronary spasm</title>

Vasoreactivity of laser-treated coronary artery was investigated in canine left circumflex coronary artery (LCx). Excimer laser (XeCl 308 nm, 50 mJ/mm2), holmium YAG laser (2.1 micrometers , 150 mJ/pulse), or argon laser (488 nm, 3 W), were used through a single optical fiber. Two 3-mm long segments were obtained from the treated segments and controls in Krebs-bicarbonate buffer. Contraction of LCx was induced with KCl at 30 mM or 3,4 DAP and expressed as developed tension (gram; g). Eighteen dogs were used. Reduction of vasocontactility was observed in excimer treated vessels (0.17 +/- 0.24 g with KCl and 0.34 +/- 0.55 g with 3,4 DAP vs 2.13 +/- 0.85 with KCl and 3.1 +/- 1.9 with 3,4 DAP in control, P < 0.001 respectively), holmium YAG treated vessels (0.43 +/- 0.48 g with KCl and 0.46 +/- 0.24 with 3,4 DAP vs 2.42 +/- 0.49 g with KCl and 3.2 +/- 0.46 with 3,4 DAP in control, P < 0.001 respectively) and argon treated vessels (0.48 +/- 0.79 g vs 4.4 +/- 0.88 in control, P < 0.001). Either pulsed or argon laser irradiation results in loss of vasoreactivity to either constrictive or relaxation agent.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.