Which statement best describes diastolic flow reversal in the arterial system?

• A. It is always an abnormal finding
• B. It is seen in and proximal to high-resistance vessels
• C. It is most commonly observed in vessels which supply low-resistance beds
• D. It can be enhanced by body heating

Answer: (B)

Diastolic flow reversal happens when the downstream vascular bed has high resistance, so during diastole the forward flow diminishes and can even reverse in the feeding artery. In arteries that supply a high-resistance bed, the impedance mismatch and wave reflections cause enough backward pressure during diastole that retrograde flow appears, and you can observe this not only in the distal vessels but also proximal to the high-resistance region. This pattern is not typical for beds with low resistance, where diastolic flow remains forward, and it wouldn’t be enhanced by body heating—warming reduces resistance and tends to promote forward diastolic flow rather than reversal.