Correlation of Intraoperative Collateral Perfusion Pressure During Carotid Endarterectomy and Status of the Contralateral Carotid Artery and Collateral Cerebral Blood Flow

Background: The optimal method for predicting when carotid shunting is not necessary during carotid endarterectomy (CEA) is controversial. This study will analyze the correlation of collateral perfusion pressure and the status of contralateral carotid/cerebral collaterals and determine whether preoperative duplex ultrasound/cerebral angiography can predict when CEA can be done without shunting. Methods: Ninety-eight patients were randomized into routine shunting and 102 into selective shunting when the collateral perfusion pressure (systolic carotid stump pressure) was <40 mm Hg during CEA. All patients had preoperative carotid duplex ultrasound and 87 had angiography, the results of which were evaluated for the presence of collateral flow from the contralateral carotid artery or posterior circulation through the anterior and/or posterior communicating arteries. Results: The perioperative stroke rate was 1.5% for the entire group. There was no correlation between preoperative symptoms and the status of the contralateral carotid artery (normal, stenosed, or occluded). The mean collateral perfusion pressure was inversely related to the severity of the contralateral carotid stenosis: 60, 57, 55, 56, and 38 mm Hg for normal, <50% stenosed, 50-69% stenosed, 70-99% stenosed, and occluded arteries, respectively (p 0.005). There was a direct relation between the number of patients with a collateral perfusion pressure of <40 mm Hg (shunted group) and the severity of the contralateral carotid stenosis: 6 of 62 (10%) for normal carotid, 7 of 43 (16%) for <50% stenosis (OR = 1.82), 12 of 69 (17%) for 50-69% stenosis (OR = 1.97), 3 of 10 (30%) for 70-99% stenosis (OR 4, CI = 0.81-19.68), and 9 of 13 (70%) for occlusion (OR 21, CI = 4.98-89.32) (p < 0.0001). None of the patients (0/56) with normal to < 70% contralateral carotid stenosis with cross-filling had a collateral perfusion pressure of < 40 mm Hg (no shunting was necessary). However, 9 of 17 (47%) patients with < 70% contralateral carotid stenosis and no cross-filling had a collateral perfusion pressure of < 40 mm Hg (p < 0.0001), whereas 6 of 7 (86%) patients with >= 70% contralateral carotid stenosis and cross-filling versus 2 of 7 (29%) with >= 70% contralateral carotid stenosis and no cross-filling had a collateral perfusion stump pressure of >40 mm Hg (p = 0.1026). Overall, 62 of 63 (98.4%) patients with cross-filling versus 10 of 24 (42%) without cross-filling had a collateral perfusion pressure of >= 40 mm Hg (p < 0.0001). Conclusions: There was an inverse correlation between collateral perfusion pressure and severity of contralateral carotid stenosis, and patients with severe contralateral carotid stenosis/occlusion were more likely to be shunted. The presence of cross-filling with normal to <70% contralateral carotid stenosis was associated with a collateral perfusion stump pressure of >= 40 mm Hg in 100% of patients for whom shunting was not carried out in our series.