Inferior Vena Caval Hemodynamics Quantified In Vivo at Rest and During Lower Limb Exercise Using Magnetic Resonance Imaging

Compared to the abdominal aorta, the hemodynamic environment in the inferior vena cava (IVC) is not well described. Using cine phase-contrast magnetic resonance imaging (MRI) and a custom MRI-compatible cycle in an open-magnet, we quantified mean blood flow rate, wall shear stress, and cross-sectional lumen area in eleven young, normal subjects at the supraceliac and infrarenal levels of the aorta and IVC at rest and during dynamic cycling exercise. Similar to the aorta, the IVC experienced significant increases in blood flow and wall shear stress as a result of exercise, with greater increases in the infrarenal as compared to the supraceliac level. At the infrarenal level during resting conditions, the IVC experienced higher mean flow rate than the aorta (1.2+/-0.5 vs. 0.9+/-0.4 L/min, p<0.01) and higher mean wall shear stress than the aorta (2.0+/-0.6 vs. 1.3+/-0.6 dynes/cm, p<0.005). During exercise, wall shear stress remained higher in the IVC as compared to the aorta, though not significantly. It was also observed that while the aorta tapers inferiorly, the IVC tapers superiorly from the infrarenal to supraceliac location. The hemodynamic and anatomic data of the IVC acquired in this study adds to our understanding of the venous circulation and may be useful in a clinical setting.