SEM Evaluation of Canine Middle Cerebral Artery Endothelium Following Microvascular Surgery

Abstract

SEM of normal arterial endothelium has shown a constant picture of fine longitudinal ridges or folds. These folds are about 15 microns across, and their smooth undulations comprise a “normal” pattern which permits assessment of various types of early endothelial damage.SEM affords rapid, stereoscopic study of relatively large areas of endothelium with ultrafine detail. Some microvascular maneuvers may mechanically distort or obliterate normal endothelial ridging. In addition, fibrin-platelet-red blood cell deposits may cover damaged endothelium.Eighty canine middle cerebral arteries, 1.0 - 1.5 mm in diameter, were studied with SEM following: a) microtourniquet and microclip occlusion, b) pinching with jeweler's forceps, c) arteriotomy and suture, d) bipolar coagulation of a side branch 1 mm from the parent artery, 20 mv for 20 seconds, and e) end-to-side microanastomosis.The initial event in arterial thrombosis is platelet adherence, and then platelet aggregation. These platelet clumps will begin to disperse or “wash out” 20 minutes post aggregation, so that 60 minutes later, platelet dispersion is fairly complete, if total arterial thrombosis and fibrin deposition have not occurred.