Hemodynamic mechanism in the angiographic disappearance of ruptured cerebral aneurysm.

Failure of unilateral carotid angiography to opacify a saccular aneurysm of the anterior communicating artery was observed; this occurred despite excellent visualization of the parent artery with spontaneous cross-filling and adequate demonstration of the intracranial carotid system bilaterally. In the absence of thrombosis of the aneurysm (which was discounted by contralateral carotid angiograms), vasospasm, and hypoplasia of the afferent arteries, a hemodynamic mechanism involving velocity of blood flow and intravascular turbulence is considered.