[An experimental study of balloon angioplasty of the canine basilar artery].

Balloon angioplasty has recently been applied to cerebral arteries but its influences on cerebral vessels are still unknown in detail. Balloon angioplasty was performed on 20 canine basilar arteries. Each artery was subjected to either one (six dogs), three (eight dogs) or ten (six dogs) balloon inflations of one-minute at three atmospheres using a 1.5 French balloon catheter. Angiograms were performed immediately after, one hour, two weeks and four weeks after angioplasty. Specimens were obtained from both angioplasty segments and non-angioplasty segments of the basilar arteries after perfusion fixation two hours (six dogs), two weeks (eight dogs) and four weeks (six dogs) after angioplasty. In addition to histological observations, the arterial diameter was measured on the angiograms and number of endothelial cells and smooth muscle cells were counted. Then, area of the vascular lumen (AL), area of the median (AM) and thickness rate of the media (TM) on the cross section were analyzed morphometrically. Stenoses of the basilar artery were frequently observed on angiograms. Histological and morphometrical findings of angioplasty segments at two hours revealed wall irregularity, medial split, slight platelet deposition and decrease in the number of endothelial cells (p < 0.01). At two weeks, smooth muscle cells were decreased (p < 0.03) and were replaced by fibrosis, but endothelial cells had regenerated to the baseline. AL was decreased (p < 0.01) and TM was increased (p < 0.01). At four weeks, fibrotic change, decrease in smooth muscle cells (p < 0.002) and increase in TM (p < 0.03) remained. Marked mural thrombus was observed in two cases at two weeks and four weeks. Balloon angioplasty caused various unfavorable changes on the canine basilar arteries both in acute and in chronic stage. This should be taken into consideration on balloon angioplasty on cerebral vessels.