Inferior Vena Cava Obstruction: Hemodynamic Consequences and Treatment

The inferior vena cava (IVC) returns ~5 L/min of deoxygenated blood from the lower body (legs, pelvis, abdomen) to the right atrium. Obstruction (thrombosis, tumor compression, IVC filter thrombosis, Budd-Chiari syndrome) causes:

• Venous Hypertension: Lower extremity edema, varices, ascites.
• Reduced Cardiac Preload: Decreased venous return → hypotension, renal hypoperfusion.
• Collateral Circulation: Dilated azygos, hemiazygos, lumbar, and abdominal wall veins (caput medusae).
• Renal Dysfunction: Impaired renal venous outflow → reduced GFR, sodium retention.

Diagnosis: Doppler US, CT/MR venography. Treatment: anticoagulation, thrombolysis, stenting, or surgical bypass depending on etiology. IVC syndrome is a vascular emergency.