The collateral function of the external carotid artery (ECA) for cerebral perfusion in cases of atherosclerotic occlusive disease of the internal carotid artery (ICA) is difficult to assess; for this reason, blood flow measurements were taken during carotid endarterectomy (CEA).
Methods
Blood flow was measured before and after CEA using a transit-time flow meter at the carotid artery in 1000 patients who underwent CEA for high-degree (>70%) ICA stenosis. The data were collected prospectively and analysed retrospectively.
Results
Median ICA blood flow increased significantly, up 46% from 160 ml min−1 (IQR: 100–234 ml min−1) before CEA to 240 ml min−1 (IQR: 187–309 ml min1) after CEA (P < 0.001). Median ECA blood flow dropped by 4%, from 152 ml min−1 (IQR: 108–220 ml min−1) to 150 ml min−1 (IQR: 103–200 ml min−1) (P = 0.001). Relative ICA blood flow volumes related to common carotid artery (CCA) flow increased from 58% before CEA to 73% after CEA, whereas relative ECA flow decreased from 54% to 44%.
Conclusions
Increased blood flow in the ICA after CEA is accompanied by decreased ECA flow whereupon the absolute amount of this redistribution is relatively limited. A more profound evaluation of these haemodynamic conditions demands further study.