ENDOTHELIAL-CELL ULTRASTRUCTURE AFTER AORTIC-ANEURYSM RUPTURE - AN ELECTRON-MICROSCOPY STUDY

Endothelial cell activation as an early response to hypovolaemic shock may be important in the pathogenesis of coagulopathy and multiple organ failure after aortic aneurysm rupture. The aim of this study was to determine whether any evidence could be found of changes in endothelial cell ultrastructure in patients undergoing operation for ruptured aneurysm and to establish a model for future studies of endothelial cells in these patients. At the start of operation, fat samples from the anterior abdominal wall were taken from five patients with ruptured abdominal aortic aneurysms and in an identical fashion from five control patients undergoing elective surgery. Endothelial cells lining capillaries were examined by transmission electron microscopy. Photomicrographs were taken of all capillaries present and these were assessed blindly by three independent observers. When compared with controls it was found that the luminal surface of the endothelial cells in patients with aneurysm rupture was more convoluted, with more frequent processes projecting into the lumen of the capillary. Budding of the luminal surface of the endothelial cell was seen in 11 of 45 capillaries in the rupture group and in none of 44 capillaries in the control group (P<0.005). Budding was seen in at least one capillary of all five patients presenting with rupture but in none of the control group (P < 0.05). In conclusion, at the ultrastructural level there are changes within endothelial cells in capillaries at an early stage after ruptured abdominal aortic aneurysm.