In vitro effects of CO₂ laser irradiation on platelets: Influence of aspirin

Laser angioplasty involves intravascular laser irradiation which may affect platelets and aggregation. In this study we examined the in vitro effects of different energy doses and modes of CO₂ laser irradiation on the platelet number, function and ultrastructure. Since aspirin is used in many patients suffering from coronary artery disease, the consequences of laser irradiation on aspirin-treated platelets were studied as well. We found that CO₂ laser irradiation causes a dose-response reduction of the platelet number that is most pronounced with high energy-short duration irradiation, and a dose-response reduction in platelet aggregation which is independent of the mode of irradiation. Pretreatment with aspirin does not change the effects of laser irradiation on platelet number, while aggregation is reduced only at relatively high energy doses. Electron microscopy revealed significant intracellular injury following low energy irradiation, while progressive damage to membranes occurred in a dose-response mode, both in untreated and aspirin-treated platelets. The clinical application of our findings should be done cautiously since important in vivo factors, such as the effect of laser irradiation on the vessel wall and coagulation system, were not studied.