Evaluation of local platelet deposition during laser thermal angioplasty

Laser thermal angioplasty is one of the brand-new transluminal interventions for arterial occlusive disease. And one of the most important prognostic factors of this intervention is the degree of local platelet deposition which causes the acute platelet thrombus and increases the proliferation of smooth muscle cells. The purpose of this study is to assess the degree of platelet deposition on the laser ablated area and to investigate the optimal conditions of laser ablation from the point of thrombogenesis. First of all, the laser ablations of various delivered energy were carried out on canine femoral arteries, then thrombus formation after laser ablation was evaluated with angioscopy. No thrombus was recognized on all ablated areas in the cases with a laser energy of 16 Joule (J) and 20 J. On the other hand, small thrombus on the ablated area was observed in 1 of 4 cases (25%) with that of 24 J, and in 2 of 4 cases (50%) with that of 30 J. Then, the degree of platelet deposition on the laser ablated area was evaluated with platelet labeled radioimmunoassay. Laser ablations were employed in canine femoral arteries varying delivered laser energy. There were no differences in the numbers of platelet deposition when the laser energy for one shot was within 24 J. The numbers of platelet deposition with a laser energy of 30 J and 45 J were significantly (p < 0.05) higher than those with a laser energy within 24 J. The numbers of platelet deposition were gradually increased related to the frequency of laser ablations, and the numbers of platelet depositions in 10 repeated laser ablations of 16 J and 20 J were significantly (p < 0.05) higher than that in single laser ablation of 16 J and 20 J. From the aspect of local platelet deposition, the optimal laser energy for one shot should be restricted within 24 J and the repeated ablation was the most appropriate method of laser thermal ablation.