Objectives: Using 30-MHz intravascular ultrasound in the human femoral artery, we related the mode of arterial remodeling to the immediate result and the mechanism of balloon angioplasty.
Background: The atherosclerotic femoral artery may undergo three modes of remodeling in response to plaque formation: compensatory enlargement, failure of compensatory enlargement and paradoxic shrinkage.
Methods: In 83 patients an ultrasound catheter pullback maneuver was performed before and after balloon angioplasty. For each lesion (n = 121), the cross section with the narrowest lumen was selected for further analysis. For each cross section, the lumen area stenosis was expressed as percent of the lumen area at an adjacent reference site. Similarly, the media-bounded area was expressed as percent of the media-bounded area at the reference site. Cross sections were classified into one of three groups based on percent relative media-bounded area: 1) > 105% (group A, compensatory enlargement, n = 24); 2) 95% to 105% (group B, failure of compensatory enlargement, n = 26); and 3) < 95% (group C, arterial wall shrinkage, n = 71). The power of the present study was 99.3% to demonstrate a difference in lumen gain of 2.5 mm2 among groups.
Results: The gain in lumen area induced by balloon angioplasty did not differ significantly among the three groups (group A, 7.0 +/- 4.0 mm2 [mean +/- SD]; group B, 8.6 +/- 4.8 mm2; group C, 8.9 +/- 4.9 mm2). Stretch of the media-bounded area was observed in all three groups, but it was significantly larger in group C (7.5 +/- 5.2 mm2) than in the other two groups (group A, 3.9 +/- 5.1 mm2; group B, 5.1 +/- 4.1 mm2). A significantly positive correlation between balloon/media-bounded area ratio and elastic recoil was observed for cross sections in groups A and B (r = 0.71 and r = 0.69, respectively). However, no correlation was observed between balloon/media-bounded area ratio and elastic recoil for cross sections in group C (r = 0.17).
Conclusions: We conclude that lumen gain by balloon angioplasty is not related to the mode of atherosclerotic arterial remodeling. However, the mode of arterial remodeling affects the dilation mechanism.