Extracranial Blood Flow Distribution During Carotid Surgery

Abstract 

Objective

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 160mlmin⁻¹ (IQR: 100–234mlmin⁻¹) before CEA to 240mlmin⁻¹ (IQR: 187–309mlmin¹) after CEA (P<0.001). Median ECA blood flow dropped by 4%, from 152mlmin⁻¹ (IQR: 108–220mlmin⁻¹) to 150mlmin⁻¹ (IQR: 103–200mlmin⁻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.

Keywords: Carotid surgery, Extra-cranial blood flow, Flow measurement, Flow distribution