[Pathologic changes at the coronary artery-bypass graft anastomosis--an immunocytochemical study]

We have performed immunocytochemical investigations on proliferative tissues observed in anastomotic sites of the saphenous vein aortocoronary bypass grafts to the coronary arteries. Nine anastomotic sites were obtained from 5 necropsy patients who had died after bypass grafting. Interval between the operation and death in these patients varied from 5 days to 9 months. The anastomotic sites were fixed in methanol-Carnoy's fixative, and embedded in paraffin. Six monoclonal antibodies specific for muscle cell actin (HHF35), smooth muscle cell actin (CGA7), vimentin, desmin, macrophages (HAM56) and endothelial cells were used for the immunocytochemical study. Of the 9 anastomotic sites, 4 were totally occluded, while the remaining 5 were patent. The occluded sites were characterized by a presence of fresh or organized thrombus. Immunocytochemically, the latter was composed of macrophages, smooth muscle cells and neovascularization. In contrast, a patent site at 5 days after grafting showed an early stage of intimal proliferation composed of macrophages and spindle-shaped cells. Two patent sites at 33 days after grafting revealed a distinct intimal thickening consisting almost entirely of smooth muscle cells. At this stage, smooth muscle cells at a deeper intima were stained positive with both HHF35 and CGA7, whereas the cells at the luminal site were stained positive with HHF35 but negative with CGA7. In older lesion at 9 months after grafting, almost all smooth muscle cells within intimal thickening showed positive with HHF35 and CGA7. Moreover, these smooth muscle cells were stained positive with vimentin but were negative with desmin, irrespective of the lesion's age.(ABSTRACT TRUNCATED AT 250 WORDS)