Echo Reference — Chamber Quantification
Right Atrial Size
Right atrial area and indexed volume severity grading by 2D method of discs and 3D echocardiography. Based on ASE 2025 Right Heart guidelines and WASE study data.
Right Atrial Area — Severity Grading
RA area is measured by planimetry in the apical four-chamber view at end-systole (maximal RA size, just before tricuspid valve opening). Trace the endocardial border excluding the area between the leaflets and annulus.
| RA Area (cm²) | Normal | Mildly Abnormal | Moderately Abnormal | Severely Abnormal |
|---|---|---|---|---|
| Threshold | < 19 | 19 – 22 | 23 – 24 | > 24 |
Indexed Right Atrial Volume (IRAV) — Severity Grading
RA volume should be measured using the method of discs (Simpson's) or 3D echocardiography. Volume is indexed to BSA. Note that 3D-derived volumes are larger than 2D-derived values — use the appropriate reference range for the method used.
2D Method of Discs
| IRAV (mL/m²) | Normal | Mildly Abnormal | Moderately Abnormal | Severely Abnormal |
|---|---|---|---|---|
| Threshold | < 30 | 30 – 36 | 37 – 41 | > 41 |
3D Echocardiography
| IRAV (mL/m²) | Normal | Mildly Abnormal | Moderately Abnormal | Severely Abnormal |
|---|---|---|---|---|
| Threshold | < 42 | 42 – 49 | 50 – 57 | > 57 |
Clinical context: RA dilatation is commonly seen with chronic tricuspid regurgitation, pulmonary hypertension, atrial fibrillation, and right ventricular dysfunction. RA size should be interpreted alongside RV size and function, TR severity, and pulmonary pressures. An enlarged RA also informs RAP estimation — IVC-based assessment may be less reliable in the setting of severe RA dilatation.
References
- Soulat-Dufour L, et al; WASE Investigators. Normal Values of Right Atrial Size and Function According to Age, Sex, and Ethnicity: Results of the World Alliance Societies of Echocardiography Study. J Am Soc Echocardiogr. 2021;34(3):286–300.
- Mukherjee M, et al. Guidelines for the Echocardiographic Assessment of the Right Heart in Adults and Special Considerations in Pulmonary Hypertension: Recommendations from the American Society of Echocardiography. J Am Soc Echocardiogr. 2025;38(3):141–186.
- Lang RM, et al. Recommendations for Cardiac Chamber Quantification by Echocardiography in Adults: An Update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging. J Am Soc Echocardiogr. 2015;28:1–39.