Impaired endothelial function after aneurysmal subarachnoid haemorrhage correlates with arginine:asymmetric dimethylarginine ratio.

BACKGROUND Endothelial dysfunction might be involved in the development of cerebral vasospasm after aneurysmal subarachnoid haemorrhage (SAH). METHODS This prospective observational study of 48 SAH subjects and 23 control subjects examined associations between reactive hyperaemia index (RHI) measured by peripheral arterial tonometry and plasma concentrations of S-100B protein, nitrite/nitrate, arginine, and asymmetric dimethyl arginine (ADMA). Clinical variables were flow velocity in the middle cerebral artery (VMCA), angiographic vasospasm, delayed neurological deficit, and 30 day survival. Five consecutive measurements were obtained at days 0-2, 3-5, 6-8, 9-11, and 12-15. RESULTS RHI was 1.67 (0.46) at days 0-2 after SAH but increased at days 3-15 to the same levels as in controls (P<0.05 compared with days 0-2). RHI was lower in subjects who died before day 30 (P=0.07), but no trends were observed in relation to angiographic vasospasm or delayed neurological deficit. Both arginine and ADMA increased after SAH compared with days 0-2 (P<0.05). S-100B was highest in non-survivors (P<0.01) and in subjects with neurological deficit (P<0.01). A positive correlation was found between RHI and arginine:ADMA ratio (r=0.43, P<0.005), but not with nitrite/nitrate, VMCA, or S-100B. CONCLUSIONS Peripheral flow-mediated vasodilation is attenuated in the first days after SAH indicating acute systemic endothelial dysfunction. Impairment of endothelial function after SAH correlates with imbalance of the arginine/ADMA pathway.