Normal Right Atrial Pressure on Echocardiography

Echocardiographic Estimation of RAP

The American Society of Echocardiography and European Association of Cardiovascular Imaging recommend using specific values rather than ranges for uniformity in reporting RAP, with normal RAP estimated as 3 mm Hg (range 0-5 mm Hg) when the inferior vena cava (IVC) diameter is < 2.1 cm and collapses > 50% with a sniff 1, 2
Intermediate RAP is estimated as 8 mm Hg (range 5-10 mm Hg) when IVC diameter and collapse do not fit the normal or elevated paradigm 1, 2
Elevated RAP is estimated as 15 mm Hg (range 10-20 mm Hg) when IVC diameter is > 2.1 cm with < 50% collapse during sniff 1, 2

The IVC should be measured from the subcostal view at 1.0 to 2.0 cm from the junction with the right atrium, using the long-axis view, perpendicular to the IVC long axis 1, 2
The inspiratory response assessment often requires a brief sniff, as normal inspiration may not elicit adequate collapse 1, 2

Hepatic vein flow patterns can be used to refine RAP estimate, with predominant forward flow during systole in normal elderly subjects without cardiac disease, and a shift to predominantly diastolic flow as RAP increases 4, 5, 6
Hepatic vein atrial reversal (Ar) increases in amplitude and duration with increasing RAP 4, 5, 6

Normal young athletes may have dilated IVC in the presence of normal pressure, which can lead to overestimation of RAP 1, 2
When hepatic venous flow shows predominant diastolic flow with increased atrial reversal, this pattern is consistent with elevated RAP in the 10-15 mm Hg range 4, 5, 6