Doppler waveforms

Doppler waveforms refer to the morphology of pulsatile blood flow velocity tracings on spectral Doppler ultrasound. Waveforms differ by the vascular bed (peripheral, cerebrovascular, and visceral circulations) and the presence of disease.

Radiographic features

Ultrasound

Doppler

Most authorities describe three types based on the number of phases of flow in each cardiac cycle ²:

• triphasic: having three phases, due to crossing the zero flow baseline twice in each cardiac cycle
  • systolic forward flow
  • early diastolic flow reversal (below zero velocity baseline)
  • late diastolic forward flow (slower than in systole)
• biphasic: having two phases or variations having forward and reverse flow ⁵
  • systolic forward flow
  • either of the following (controversial):
    • diastolic flow reversal without late diastolic forward flow (more common)
    • zero diastolic flow reversal and pandiastolic forward flow (slower than in systole)
• monophasic: having one phase
  • systolic forward flow continuing into diastole, lacking reverse diastolic flow, which can be divided by acceleration/deceleration time ⁸:
    • sharp: fast systolic rise and fast diastolic fall
    • blunted: slow systolic rise and slow diastolic fall

Triphasic arterial flow is considered normal in peripheral arteries and monophasic flow is considered abnormal ⁷. Due to the controversy surrounding the definition of biphasic, there is disagreement about whether biphasic flow is normal ². Diastolic flow reversal is generally considered normal but pandiastolic forward flow is abnormal in the peripheral arteries ². These categorizations differ for the cerebrovascular and visceral circulations, which normally have lower resistance.

Pulsatile venous flow is considered abnormal and is suggestive of elevated pressures in the right atrium ⁶.