Assessment of regional vascular distensibility in diseased iliofemoral arteries by intravascular ultrasound.

The influence of atherosclerosis on distensibility of iliac and superficial femoral arteries was assessed retrospectively in 28 patients using intravascular ultrasound. Distensibility was related to lesion morphology, lesion geometry, percentage area stenosis, effect of balloon angioplasty, hypertension and patient's age. In 10 patients, free lumen area remained unchanged during the cardiac cycle. From the remaining 18 patients, a total of 135 cross-sections underwent qualitative and quantitative analysis. Cross-sections without a lesion were compared with those showing; soft/hard and eccentric/concentric lesions. At normal sites, iliac arteries showed greater distensibility than femoral arteries (6.5 +/- 2.4% vs. 3.5 +/- 0.9%; p < or = 0.05). Hard lesions in iliac arteries were less distensible than lesions; in femoral arteries this difference was less pronounced. Lesion geometry did not influence arterial distensibility. Intravascular ultrasound revealed no difference in distensibility when normal cross-sections were compared with those having a < 50% or a 50% to 90% area stenosis. In contrast, a significant decrease in femoral artery distensibility was found in the presence of > 90% stenosis (0.4%). Comparison of cross-sections before and after balloon angioplasty revealed a marked increase in distensibility of iliac arteries following intervention; in the femoral artery, there was practically no change in distensibility. Hypertension and increasing age proved to have no significant influence on arterial distensibility. This study demonstrates that intravascular ultrasound is potentially a powerful tool to assess arterial distensibility and the influence of atherosclerosis on vascular dynamics.