Endothelial cell damage by temporary arterial occlusion with surgical clips

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Abstract
The effects of temporary vascular occlusion with surgical clips on the underlying endothelial lining were studied with scanning (SEM) and transmission (TEM) electron microscopy. Both common carotid arteries were exposed in 25 anesthetized rabbits. A Heifetz clip was used to occlude the right carotid artery for 5, 15 and 30 min, and 2 h in 5 animals each. The clips were removed and the vessels immediately perfused with glutaraldehyde. In the 5 remaining animals, the right carotid arteries were occluded for 30 min followed by removal of the clip and resumption of blood flow for 30 min prior to fixation. Combined SEM and TEM examination of the endothelium of compressed segments revealed craters, balloons, blebs, vacuoles, swollen mitochondria, dilated granular endoplasmic reticulum and subendothelial edema. There were areas of endothelial cell flattening, discontinuity and desquamation exposing the subendothelial tissues. Following restoration of flow, platelets and fibrin were found adherent to altered endothelial cells and to exposed subendothelial tissues. Endothelial craters and balloons were found distal and, significantly less frequently, proximal to the site of occlusion. Antiplatelet aggregating agents may prove beneficial for the prevention of thrombus formation at the site of the clip as well as craters and balloons distal to the clip following procedures requiring temporary vascular occlusion.