Assessment of vasospasm in experimental subarachnoid hemorrhage in rats by selective biplane digital subtraction angiography.

Although the rat subarachnoid hemorrhage model is well established in vasospasm research, the angiographic evaluation is difficult due to the animal's small size. For this reason, the aim of the study was to develop a standardized angiographic examination technique without additional complex equipment. Under general anesthesia, 11 Sprague-Dawley rats underwent selective cerebral digital subtraction angiography using a 0.3 mm focal spot and a 2.0-fold linear magnification. Five animals had experimental subarachnoid hemorrhage according to the "double-hemorrhage" model. Comparison with the intraarterial tip of the microcatheter enabled calibration of the vessel lumen. The diameter of the normal basilar artery (n=6) was 0.34+/-0.03 mm (mean+/-SD), whereas delayed vasospastic constriction (mean 6.2 days) caused a reduction in diameter of 32.4% (0.23+/-0.09 mm) as well as impaired collateral blood flow via the posterior communicating artery and anterior spinal artery. Histological examination of sections stained with hematoxylin and eosin under a light microscope confirmed vasospasm. In conclusion, biplane digital subtraction angiography allows precise and reliable evaluation of arterial diameter reduction and hemodynamic parameters in a rat vasospasm model. However, further investigation is required for assessment of vasoactive drugs, e.g., endothelin receptor antagonists.