Endothelial cell activation after subarachnoid hemorrhage

Evidence from animal experiments suggests that endothelial cell activation plays a pathogenetic role in the development of cerebral ischemia after subarachnoid hemorrhage (SAH). We measured plasma concentrations of two markers of endothelial cell activation, i.e., ED1-fibronectin (ED1-fn) and von Willebrand factor (vWf), among patients with aneurysmal SAH. We analyzed the relationships of concentrations to initial clinical conditions, treatment modalities, and the occurrence of delayed cerebral ischemia.

We collected 123 blood samples from 27 patients with aneurysmal SAH. Aneurysms were treated surgically in 19 cases, were treated endovascularly in 7 cases, and remained untreated in 1 case. Twelve patients developed symptomatic delayed cerebral ischemia.

Initial concentrations of ED1-fn (4.3 +/- 3.7 microg/ml) and vWf (17.8 +/- 8.2 microg/ml) were higher than the reference values (ED1-fn, 1.7 +/- 0.9 microg/ml, P < 0.001; vWf, 11.5 +/- 5.2 microg/ml, P = 0.003). Concentrations were higher among patients in poor clinical condition at admission, compared with patients in good clinical condition (mean difference, ED1-fn, 5.7 microg/ml, P = 0.04; vWf, 10.4 microg/ml, P = 0.02). Levels of both markers increased significantly after surgery (mean increase, ED1-fn, 7.5 microg/ml, P = 0.01; vWf, 13.2 microg/ml, P = 0.05) and after ischemic episodes (mean increase, ED1-fn, 8.3 microg/ml, P = 0.02; vWf, 5.0 microg/ml, P = 0.04).

Plasma concentrations of markers of endothelial cell activation were increased early after SAH and were significantly associated with the clinical condition at admission. We also observed a significant increase in concentrations after surgery and after ischemic episodes. Whether endothelial cell activation is a causal or indirectly related factor in the pathogenesis of delayed cerebral ischemia after SAH is still uncertain.