Figure 3.

Distribution forces of the contrast medium in the inferior vena cava. A: Phlebography in neutral breathing; B: Phlebography during the Valsalva maneuver that shows distribution of the contrast medium to renal and iliac veins; C: Computational study of inferior vena cava migration forces using an experimental set up and finite element simulation during the Valsalva maneuver. When the patient is asked to perform a Valsalva maneuver, the inferior vena cava blurs as the contrast is displaced to lower pressure areas, such as iliacs and renal veins.