[Experimental model producing global brain ischemia by clamping the aorta in dogs]

Canine cerebral blood flow is supplied not only through carotid and vertebral arteries, but also through rich network of collaterals. Therefore, it is said that total body arrest is requested to assure the global brain ischemia. The global ischemic models, reported previously, were by the simultaneous occlusion of aorta and vena cava. In our model, however, the global cerebral ischemia was produced by clamping only the ascending aorta. Cardiovascular changes such as increases in left ventricular and pulmonary arterial pressure, and decrease in left ventricular dp/dt followed after ceasing of ascending aortic blood stream. The heart continued to beat during 60 minutes of the clamping. Despite of increased central venous pressure, sagittal sinus pressure and intracranial pressure remained unchanged during the aorta clamping. Ten-minutes of total cerebral ischemia was produced in 46 dogs and successful studies on cerebral and systemic variables were carried out in 68% of them. The method of clamping the aorta without occlusion of vena cava seems to be unsuitable for long term survival study because of severe loading of lung circulation. However, we conclude that this simple model is of great use for short term experiment on global brain ischemia.