** Less than 3.5.

Abnormal Findings (Stenosis)

• Increased PSV: A velocity greater than 200 cm/s often suggests a significant stenosis (greater than 60% narrowing).
• Tardus-Parvus Waveform: A "slow rising" and "low amplitude" pulse distal to a stenosis, indicating that the blockage is preventing normal flow velocity.
• **Elevated R