Ventricular remodeling after acute myocardial infarction: Effect of low-intensity laser irradiation

Background and Objective: Low-intensity laser irradiation is claimed to enh ance wound healing. Healing after myocardial infarction results in ventricu lar enlargement and wall thinning. If laser treatment accelerated cardiac h ealing, we speculated that ventricular remodeling would be attenuated. Study Design/Materials and Methods: In vitro, fibroblasts were irradiated f or 1 minute twice a day for 4 days (5 mW; wavelength, 780 nm). One day afte r infarction, rats were randomly assigned to 5 or 10 mW transdermal irradia tion twice a day for 4 days or to sham. One week after infarction, we measu red the remodeling parameters; cavity volume, infarct thickness, and vascul ar structure, and the healing parameters; collagen content and inflammation . Results: Laser-treated fibroblasts occupied more area than controls. Hearts receiving the 10 mW treatment had smaller volumes than sham hearts. Laser treatment reduced infarct thinning and preserved arterial lumen area; howev er, collagen was not increased and inflammation was inhibited. Conclusions: Low-intensity irradiation attenuated infarct-associated remode ling. In contrast to expectations from in vitro study, these effects were n ot a result of enhanced healing. (C) 2000 Wiley-Liss, Inc.