A waveform in the context of Doppler ultrasound refers to the spectral display that shows how blood flow velocity changes over the cardiac cycle. The shape, pattern, and characteristics of the waveform provide essential diagnostic information about the vessel being examined and the vascular bed it supplies. High-resistance waveforms (with sharp systolic peaks and little diastolic flow) are normal in arteries supplying resting muscles, such as the external carotid and femoral arteries. Low-resistance waveforms (with continuous diastolic flow) are normal in arteries supplying organs that need constant blood flow, such as the internal carotid and renal arteries. Venous waveforms reflect the influence of respiration and cardiac activity on venous return. Changes in waveform pattern from the expected normal are key to diagnosing stenosis, occlusion, thrombosis, and other vascular conditions.
Sonography Term