Objective To explore the impact of contrast agent concentration on the excimer laser's effect on plaque ablation.Methods Using a laser catheter with a diameter of 0.9 mm,we conducted plaque model ablation experiments employing a 308-nanometer xenon chloride excimer laser.During the excimer laser ablation process,five groups were formed based on the injected contrast agent concentrations:a saline group,25%concentration group,50%concentration group,75%concentration group,and 100%concentration group.Optical coherence tomography was utilized to assess the changes in plaque lumen area after excimer laser ablation,evaluating the impact of contrast agent concentration on the excimer laser's ablation efficacy.Simultaneously,a water manometer was used to measure the shockwave pressure generated by the excimer laser in liquids with different contrast agent concentrations,aiming to explore the correlation between the shockwave pressure of the excimer laser and its ablative effect.Results The ablation areas in the 75%concentration group and the 100%concentration group were similar(P>0.05),both exceeding those in the 50%concentration contrast agent group,25%concentration group,and saline group(all P<0.001).Specifically,the ablation area in the 50%concentration group was significantly larger than that in the 25%concentration group and saline group(both P<0.001),while the 25%concentration group was larger than the saline group(P<0.001).The influence of contrast agent concentration on the shockwave pressure of the excimer laser exhibited a similar trend.Additionally,there was a significant positive correlation between the shockwave pressure generated by the excimer laser and its ablation area(r=0.9987,P<0.001).Conclusions The intensity of excimer laser ablation on plaque tissue can be modulated by altering the contrast agent concentration.These findings offer guidance for the application of excimer laser in conjunction with contrast agent injection techniques in the treatment of coronary artery disease.