DOES SEQUENTIAL BALLOON INJURY OF AN ARTERY LEAD TO A DIFFERENT OUTCOME THAN A SINGLE INJURY - AN EXPERIMENTAL-STUDY OF ANGIOPLASTY

Background Mechanisms of stenosis after angioplasty are often studied in experimental models created by injury of normal arteries, Sequentia l rather than single insult may provide the better model, We compared the response of arteries to these two types of injury. Methods Two gro ups of arteries of cholesterol-fed New Zealand white rabbits were comp ared: single balloon injury arteries and two sequential balloon injury arteries (14-day interval between injuries). At 1-49 days after the f irst injury lumen dimensions and number of cells and cell proliferatio n in the media and neointima were assessed. Results Single injury resu lted in cell proliferation in the artery wall, formation of neointimal , and progressive loss of lumen diameter. In sequentially injured arte ries, the second injury caused an immediate increase in angiographic l umen diameter from 1.6 +/- 0.1 mm to 2.0 +/- 0.1 mm but the lumen decr eased to 1.3 +/- 0.3 mm by 28 days after the second injury, consistent with restenosis. At late time points after injury the lumen diameter was similar in the two groups of arteries, The sequential lesion neoin timal area increased at the same rate as the primary lesion neointimal . The second of the sequential injuries stimulated cell proliferation activity in the vessel wall that was similar in magnitude to that seen after primary injury. Conclusions These findings suggest that the pri mary injury process initiated mechanisms that determine the rate of ne ointimal area formation and lumen dimensions over the 5-6 week time in terval studied here, The second of the sequential injuries initiated a cell proliferation response in the artery wall but did not alter the neointimal area or lumen caliber consequences of primary injury.