What is the flow characteristic within the external carotid artery (ECA)?

The flow characteristic within the external carotid artery (ECA) is classified as high resistance. This is primarily due to the ECA supplying blood to several branches that are associated with structures that do not have high metabolic demands. These branches include the facial artery and others that primarily supply skin and muscles of the neck and face. High resistance flow is indicated by a sharp systolic upstroke and a dicrotic notch in the Doppler waveform, consistent with the flow patterns observed in the ECA. In contrast, internal carotid arteries, which supply the brain, typically exhibit low resistance characteristics because of the high metabolic needs of brain tissue, leading to continuous forward flow without significant fluctuation.

Understanding the resistance patterns of different arterial supplies helps in assessing vascular conditions and conducting Doppler evaluations effectively.