Vascular and Hemodynamic Changes Induced by Experimental Subarachnoid Hemorrhage

Objective: In this experimental subarachnoid hemorrhage (SAH) model, pathophysiological processes that accompany acute vasospasm, morphological changes in the basilar artery, and the effect of altered cerebral blood flow (CBF) on mortality were examined. Material and Methods: In the hemorrhage group of rats (n= 51), experimental subarachnoid hemorrhage was induced and mean arterial pressure (MAP) and cerebral blood flow (CBF) measurements were performed following bleeding. Histopathological assessments were performed in controls (n= 7) as well as in rats surviving for 72 hours. Results: An abrupt reduction of 63.2% +/- 10% was observed in CBF, followed by 38.1 +/- 13% and 29.1 +/- 11% lower values as compared to baseline at 35 and 60 minutes, respectively (p < 0.001). The average CBF following hemorrhage was significantly lower in rats that died within the first 24 hours and than those that survived for 3 days (p < 0.01). Histopathological examination showed thickening in arterial walls, reduced vessel lumen diameter, and vasculopathy findings. Conclusion: Our findings suggest that following subarachnoid bleeding the fall in CBF alone does not impact the mortality rates and that the duration of the reduction in CBF seems to represent an important prognostic factor for survival.