Which waveform finding most strongly suggests collateral flow with low peripheral resistance?

Which waveform finding most strongly suggests collateral flow with low peripheral resistance?

• A. Monophasic with broad systolic peak and continuous forward diastolic flow
• B. Triphasic with sharp diastolic reversal
• C. Biphasic with brief diastolic reversal
• D. High-resistance with minimal diastolic flow

Answer: (A)

Downstream resistance shapes Doppler waveforms. When the distal bed has low resistance, the flow is less pulsatile and shows continuous forward diastolic flow, often with a broad, damped systolic peak. Collateral pathways supplying the limb create that low-resistance channel, so the waveform becomes monophasic with sustained diastolic forward flow. This pattern best reflects collateral flow with low peripheral resistance. The other patterns indicate higher resistance or more pulsatile flow without the low-resistance collateral bed: triphasic with diastolic reversal shows high resistance, biphasic with brief diastolic reversal indicates intermediate resistance, and high-resistance with minimal diastolic flow indicates very limited forward flow.

Downstream resistance shapes Doppler waveforms. When the distal bed has low resistance, the flow is less pulsatile and shows continuous forward diastolic flow, often with a broad, damped systolic peak. Collateral pathways supplying the limb create that low-resistance channel, so the waveform becomes monophasic with sustained diastolic forward flow. This pattern best reflects collateral flow with low peripheral resistance. The other patterns indicate higher resistance or more pulsatile flow without the low-resistance collateral bed: triphasic with diastolic reversal shows high resistance, biphasic with brief diastolic reversal indicates intermediate resistance, and high-resistance with minimal diastolic flow indicates very limited forward flow.