If you see a slow upstroke and no diastolic flow in the CCA, what location is likely affected by disease?

The observation of a slow upstroke and the absence of diastolic flow in the common carotid artery (CCA) suggests a specific location affected by vascular disease. When these characteristics are noted, it typically indicates that there is an issue that is impeding normal blood flow, which is usually due to significant stenosis or occlusion.

When disease is present proximal to the CCA, it can affect the hemodynamics of the blood flow enough to create these findings. A lesion or narrowing before the CCA can result in turbulence and increased resistance, which diminishes the upstroke and may entirely eliminate diastolic flow due to high-grade stenosis or complete occlusion. This is distinct from disturbances or conditions located further downstream, where the resting diastolic flow might still be preserved or where changes in the waveforms would reflect different pathophysiological conditions.

Thus, the presence of these particular venous waveform characteristics strongly implies that the pathology is indeed proximal to the CCA, as opposed to within the CCA or downstream, where different flow patterns would likely be observed.