VENOUS

WAVEFORM TERMS

WAVERFORM MODIFIERS

NORMAL VENOUS WAVEFORMS

Normal venous flow in the larger peripheral and more central veins is spontaneous with low-velocity Doppler waveforms that reflect pressure gradient changes produced by respiratory and cardiac function.

Flow velocities are very low in the smaller veins distally in the extremities and may not produce discernable Doppler signals in the resting state.
Throughout the periphery, flow velocities vary with respiration 2/2 changes in intrathoracic and intraabdominal pressures (respirophasic). These patterns of respiratory variations in flow velocity can be suspended, severely dampened or absent with shallow breathing or breath holding.
Peripheral veins that are most distal to the heart (calf or forearm veins) demonstrate less spontaneity and respirophasicity compared to the veins closer to the heart. Cardiac filling and contraction also draws and pushes venous flow, with this influence normally stronger in veins closest to the heart termed pulsatile flow.

ABNORMAL VENOUS WAVEFORMS

Evaluation includes appraisal of flow direction, responses to respiration and cardiac function, and response to physiologic maneuvers.
Symmetry is your friend! Changes 2/2 central or systemic conditions are seen bilaterally. Use contralateral side for comparison.
Normal antegrade flow direction in the venous system may become retrograde when there is valvular incompetence or occlusion in more central venous segment.
Continuous venous flow suggests a more central obstruction.
Pulsatility is not normally seen in lower extremity peripheral veins 2/2 distance from heart. Loss of pulsatility in central upper extremity and abdominal veins however is abnormal.
Interpretation of venous waveform morphology is most often done w/o reporting angle corrected velocity data although measuring velocities is essential when evaluating a fistula or venous stenosis.

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