Hemodynamic changes in the head and neck after ligation of the unilateral carotid arteries: a study using color Doppler imaging.

For evaluation of the hemodynamics of the collateral circulation to the ligated external carotid artery (ECA) region, we measured the blood flow direction and volume in branches of the ECA in patients with unilateral carotid artery ligation before and during digital suppression of the common carotid artery (CCA) on the ligated and nonligated sides with color Doppler imaging and angiography. The main collateral pathway to the ligated ECA region was the ipsilateral occipital artery through Richter's anastomosis from the vertebral artery in the case of unilateral ECA ligation, and was the contralateral carotid artery in the case of unilateral CCA, ECA, and internal carotid artery resection. The superior and inferior labial arteries were important as the collateral pathway from the contralateral ECA.