[Intravenous ultrasonography as a method for imaging the morphoanatomical effects of coronary angioplasty]

Despite the therapeutic success of percutaneous transluminal coronary angioplasty (PTCA), the mechanisms by which PTCA increase vessel luminal size remain uncertain. To better understand the transmural morphologic changes associated with PTCA of stenosed coronary arteries, we studied with a high-frequency intravascular ultrasound catheter 18 coronary artery segments in 18 patients following balloon angioplasty. High-quality cross-sectional images were obtained from 15 coronary sites without complications in all patients. Two distinctive morphologic features following balloon angioplasty were appreciated by intravascular ultrasound imaging. The first pattern, observed in 10 cases (67%), consisted of a stretched plaque without any evidence of dissection. The second pattern, found in 5 cases (33%), demonstrated a dissection of the plaque ranging from a radial tear with separation of the 2 ends of the plaque to an extensive dissection which, in 1 case, encompassed the entire circumference of the artery. Although angiography showed a good post-angioplasty result in all cases, intravascular ultrasound evidenced a large amount of residual atheroma occupying the artery cross-sectional area. In addition, this imaging modality revealed more often than angiography the presence of calcification and dissection. These data demonstrate that PTCA creates different morphologic patterns which are related to the mechanisms of lumen enlargement and that the coronary artery anatomy after dilatation is much more complex than that observed with angiography. This study confirms that intravascular ultrasound is a feasible and safe imaging modality which provides new valuable insight into the mechanisms by which angioplasty improves vessel patency.