Evaluation of haemodynamic effects of extracranial-intracranial arterial bypass in unilateral internal carotid artery occlusion.

Sixty-four patients with unilateral atherosclerotic occlusion of the internal carotid artery were studied at the Bakulev Institute for Cardiovascular Surgery with transcranial Doppler (TCD) ultrasonography and angiography before and after extracranial-intracranial arterial bypass (EIAB). TCD assessed accurately the extent of the collateral circulation in 95% of cases. The haemodynamic effectiveness of EIAB depends on the preoperative state of the collateral circulation; the greatest effect was achieved in patients with the lowest levels. EIABs improved the outcome in patients in the present series; hence vascular and neurosurgeons may be persuaded of the benefit of this treatment in patients with unilateral atherosclerotic occlusion of the internal carotid artery.