Venous drainage delay assessed by angiography during balloon test occlusion in 60 patients undergoing permanent internal carotid artery occlusion
| Venous Drainage Delay* | 0 Seconds | 1 Second | 2 Seconds | 3 Seconds | Total |
|---|---|---|---|---|---|
| Aneurysms | 26 | 6 | 2 | 1 | 35 |
| Tumors | 16 | 4 | 1 | 2 | 23 |
| Direct fistulae | 2 | 0 | 0 | 0 | 2 |
| Total | 44 | 10 | 3 | 3 | 60 |
* Beginning of venous phase is determined by appearance of first cortical veins at the angiogram. Venous drainage delay corresponds to cortical vein–filling delay of the occluded territory compared to the injected artery (contralateral internal carotid artery or dominant vertebral artery).