Arterial response during cutting balloon angioplasty: a volumetric intravascular ultrasound study.

BACKGROUND AND PURPOSE: Previous studies have demonstrated that the mechanism of acute lumen enlargement after balloon angioplasty is a combination of vessel expansion and plaque redistribution, but not plaque compression. The purpose of this study was to clarify, from a three-dimensional aspect, the vascular response to cutting balloon angioplasty. METHODS: Serial intravascular ultrasound (IVUS) studies, including pre- and post-intervention, were performed in 36 native coronary lesions treated with the cutting balloon device. External elastic membrane (EEM), lumen, and plaque + media cross-sectional area were measured at 16-frame intervals (30 frames = 1 mm) over a lesion length of 16 mm with the center on the smallest pre-intervention lumen area. Volumetric calculations were based on Simpson's rule. RESULTS: EEM volume (261.16 +/- 89.59 vs. 279.59 +/- 85.92 mm3; p < 0.01) and lumen volume (106.48 +/- 37.83 v.s. 133.72 +/- 36.57 mm3; p < 0.01) significantly increased after cutting balloon angioplasty. Furthermore, the plaque + media volume throughout the lesion changed significantly after cutting balloon angioplasty (154.68 +/- 63.36 vs. 145.87 +/- 59.20 mm3; p < 0.01). The change in lumen volume correlated strongly with the change in EEM volume (r = 0.75; p < 0.01), but poorly with the change in plaque + media volume (r = 0.08; p = 0.64). Less longitudinal plaque redistribution was also observed throughout the vessel after angioplasty. CONCLUSION: The results of this study indicate that the predominant mechanism of lumen enlargement from cutting balloon angioplasty is vessel expansion, although total plaque mass reduction and longitudinal plaque redistribution do occur.