What is the normal Doppler characteristic in the common carotid artery (CCA)?

The common carotid artery (CCA) typically demonstrates a low resistance Doppler waveform pattern. This characteristic is primarily due to the fact that the CCA supplies blood to the brain, which requires a more continuous flow of oxygenated blood to meet the brain's metabolic needs. Low resistance waveforms indicate that there is less impedance to blood flow, meaning that the vascular bed at the end of the arterial system (in this case, the cerebral circulation) allows for a steady, uninterrupted flow.

While the choices mention mixed resistance as a possible option, the CCA does not show mixed characteristics. The flow pattern in the CCA is predominantly low resistance rather than showing fluctuations indicative of mixed resistance. Other areas, such as the peripheral arteries, may exhibit mixed or high resistance due to the varying demand for blood but not the CCA.

Understanding these characteristics helps clarify the physiological demands placed on the CCA in providing adequate cerebral perfusion and supports the interpretation of Doppler ultrasound findings in vascular studies.