Inferior vena cava echocardiography.

The inferior vena cava can be imaged during echocardiography from the subcostal transducer position as an echo-free space at a depth ranging from 6 to 15 cm from the abdominal wall. The normal inferior vena cava M-mode echocardiogram has a "a" and "v" pulsation pattern similar to that seen in the jugular venous tracing and exhibits prominent cyclic respiratory changes. Since right atrial activity can be seen as a pulsation on the M-mode inferior vena cava tracing, specific patterns can be observed during cardiac arrhythmias. In right heart failure the inferior vena cava is usually distended, with diminished respiratory collapse. In tricuspid regurgitation, contrast injected into an arm appears in the inferior vena cava during the "v" wave. "A-wave synchronous" inferior vena cava contrast or a contrast appearance unrelated to the cardiac cycle, frequently with deep inspiration, does not suggest tricuspid regurgitation.