HISTOLOGICAL AND MORPHOMETRIC ANALYSES OF EARLY AND LATE AORTOCORONARY VEIN GRAFTS AND DISTAL ANASTOMOSES

BACKGROUND: Aortocoronary vein grafts develop fibromuscular intimal hy perplasia within the first year of implantation. Tissue remodelling ma y promote development of graft atherosclerosis and thrombosis. Angiogr aphic studies show that human aortocoronary vein grafts in situ for on e or more years become stenosed, preferentially at the distal anastomo sis versus the body or trunk of the graft or at the proximal anastomos is. Previous studies have not reported morphological data on the natur e and distribution of intimal lesions around the distal graft/artery a nastomoses. OBJECTIVE: To examine and quantify histological and morpho metric changes within the intima of 27 aortocoronary vein grafts and t heir distal anastomoses. METHODS: Seventy-two hearts obtained at autop sy and one at heart transplantation were examined, photographed and fi xed in 10% buffered formaldehyde solution. Three to seven 3 mm long se gments of grafts and their distal anastomoses were sectioned, stained and examined by light microscopy. RESULTS: Eleven early grafts were im planted for six weeks or less, and they showed significant cellular hy perplasia mainly at the suture line. In 16 late grafts in situ 1.5 to 15 years, the degree of fibromuscular intimal thickening was greatest on the hood and at the suture line, whereas on the floor of the native artery and in the graft body the degree of thickening was approximate ly one-third and two-thirds, respectively, that seen on the hood. CONC LUSIONS: Stenosis of aortocoronary vein grafts at their distal anastom osis is likely related to the preferential development of intimal thic kening on the hood of the graft and at the suture line. Because fibrom uscular intimal hyperplasia has been reported to play a role in the de velopment: of atherosclerosis and thrombosis in the body of vein graft s, this focal hyperplasia at the distal anastomosis may also play a ro le in vein graft failure.