What waveform characteristics in CCA with distal disease?

• A. Sharp, Narrow Systolic Peaks With Absent Diastolic
• B. Broad Systolic Peak With Preserved Diastolic
• C. Normal Triphasic
• D. Low Diastolic Flow

Answer: (A)

When the disease is distal to where you’re measuring, the downstream vascular bed has higher resistance. That reduces runoff during diastole, so diastolic forward flow becomes diminished or absent. At the same time, the systolic portion of the waveform can appear as a brief, sharp peak because the forward flow is concentrated into a shorter systolic window. This combination—an abrupt, narrow systolic peak with no diastolic flow—fits a distal high-resistance pattern.

Normal triphasic or a broad, rounded systolic peak with preserved diastolic suggests normal or low-resistance downstream flow, and simply having low diastolic flow without the accompanying abrupt systolic peak wouldn’t as specifically reflect distal disease.