The International Subarachnoid Aneurysm Trial (ISAT) found that endovascular coiling of an aneurysm that has bled,when accessible to such a coiling procedure, was just as efficacious as and safer than surgical clipping. In this procedure, the placement of endovascular coils within the aneurysm induces electrothrombosis, and obliteration, of the aneurysmal sac