Assessment of saphenous vein graft wall characteristics with intravascular ultrasound imaging

Abstract

The wall characteristics of saphenous vein grafts (SVGs) after coronary artery bypass grafting (CABG) were assessed with intravascular ultrasound (IVUS) imaging. Twenty-seven SVGs in 25 patients who had undergone CABG were studied with IVUS in vivo. Ten SVGs excised from 6 patients who had undergone reoperation were studied with IVUS in vitro. The results were compared with the histopathologic findings. IVUS images of four SVGs studied within 1 month after CABG showed a thin and single-layer structure, which was almost identical to the IVUS features of a normal, fresh SVG. In five SVGs studied between 3 months and 1 year after CABG, the wall thickness was increased, and there were hypoechoic areas. In sixteen SVGs studied more than 2 years after CABG, two patterns were noted on IVUS imaging. One pattern was a triple-layer structure of alternating hyperechoic, hypoechoic, and hyperechoic bands seen in the angiographically normal sections of the SVGs. The second pattern was a heterogeneous, echogenic monolayer found in the angiographically irregular and diseased sections of the SVGs. Comparison of the in vitro IVUS images with the histopathology of the SVGs showed a strong correlation between the triple-layer structure and fibrointimal proliferation, and between the heterogeneous monolayer and atherosclerosis. In conclusion, IVUS is useful for assessing SVGs and for long-term qualitative monitoring of vein graft disease after CABG.