EFFECT OF BALLOON ANGIOPLASTY ON FEMORAL-ARTERY EVALUATED WITH INTRAVASCULAR ULTRASOUND IMAGING

Background. Intravascular ultrasound was used to assess the immediate effect of balloon angioplasty on the superficial femoral artery. Methods and Results. In 16 consecutive patients, corresponding ultrasonic cross sections (n=72) before and after balloon angioplasty were qualitatively and quantitatively analyzed. The qualitative data were compared with angiographic findings. Before intervention, the angiographically demonstrated obstructive lesions were confirmed by intravascular ultrasound. Ultrasound enabled discrimination between soft (n=43) and hard (n=29) lesions, as well as between eccentric (n=57) and concentric (n=15) lesions. After balloon angioplasty, the presence of a dissection assessed angiographically in 14 patients was confirmed by intravascular ultrasound. Additional morphological information provided by ultrasound included plaque rupture in 14 patients and internal lamina rupture in six patients. Quantitative ultrasound data revealed an increase in free lumen area from 9.7+/-4.7 to 18.3+/-7.0 mm2 (p less-than-or-equal-to 0.01), an increase in minimal lumen diameter from 2.8+/-0.7 to 3.6+/-1.2 mm (p less-than-or-equal-to 0.01), and an increase in media-bounded area from 21.7+/-5.4 to 28.3+/-5.8 mm2 (p less-than-or-equal-to 0.01). The lesion area for the majority of cases (n=32) remained unchanged (13.0+/-4.9 mm2 versus 12.9+/-4.6 mm2), or the lesion disappeared partially (from 9.1+/-0.9 to 4.3+/-1.4 mm2, n=4, p less-than-or-equal-to 0.01) or totally (from 10.1+/-4.2 to 0 mm2, n=6). Stretching of the arterial wall was further evidenced by medial thinning from 0.55+/-0.19 to 0.34+/-0.11 mm (p less-than-or-equal-to 0.01). Conclusions. Luminal enlargement by balloon dilatation is achieved primarily by overstretching the arterial wall, with the lesion volume remaining practically unchanged. Overstretching is accompanied almost always by dissection and plaque rupture and occasionally by an internal lamina rupture.