What does the absence of end diastolic flow in the common carotid artery (CCA) spectral Doppler waveform indicate?

The absence of end diastolic flow in the common carotid artery (CCA) spectral Doppler waveform is indicative of a serious pathology, such as distal occlusion of the internal carotid artery (ICA). When there is an occlusion in the ICA, the normal antegrade flow in the CCA can be disrupted, leading to a change in the Doppler waveform. Specifically, as the ICA becomes occluded, the blood flow may not be sufficient to maintain a continuous flow pattern, resulting in the absence of end diastolic flow in the CCA.

In pathological states such as significant stenosis or occlusion, the blood flow dynamics are altered. If the ICA is occluded, the vascular supply to areas typically fed by this artery is compromised, which can lead to diminished or absent flow in the CCA. This situation is clinically significant because it can signal an increased risk of cerebrovascular accidents due to inadequate blood supply to the brain.

Normal arterial function would show a typical Doppler waveform with continuous forward flow throughout the cardiac cycle, and proximal stenosis would typically show altered flow patterns that do not include complete loss of end diastolic flow but may have decreased diastolic velocity. Venous occlusion presents entirely different Doppler signals