How can I differentiate the right ventricle (RV) from the left ventricle (LV) on echocardiography?

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Differentiating RV from LV on Echocardiography

The right ventricle is distinguished from the left ventricle on echocardiography by identifying the moderator band and heavy trabeculations within the RV cavity, the tricuspid valve (which is more apically positioned than the mitral valve), and the characteristic crescent or triangular RV shape that wraps around the ellipsoid LV. 1

Key Anatomical Features to Identify the RV

Structural Characteristics

  • Heavy trabeculation and moderator band: The RV is highly trabeculated with several prominent muscle bands, including the septoparietal trabeculations and the moderator band—a distinctive feature not present in the LV 1

  • Three-part anatomy: The RV consists of three distinct sections: the inlet (from tricuspid valve to proximal infundibulum), the apical trabecular body, and the outlet (RV outflow tract to pulmonary valve) 1

  • Thin free wall: The RV free wall measures only 2-3 mm in thickness, significantly thinner than the LV wall 1

  • Crescent/triangular shape: The RV forms a hemi-ellipsoid or crescent shape that wraps around the more circular, ellipsoid LV 1

Valve Identification

  • Tricuspid valve position: The tricuspid valve annulus inserts more apically (closer to the apex) than the mitral valve annulus—typically 5-10mm more apical in the apical four-chamber view 1

  • Crista supraventricularis: This unique muscle bridge separates the RV inflow (tricuspid annulus) from the outflow tract (pulmonic annulus), a structure not present in the LV 1

Systematic Approach to Chamber Identification

In the Apical Four-Chamber View

  • Identify which ventricle is anterior: The RV is positioned anteriorly (closer to the chest wall/transducer), while the LV is posterior 1

  • Look for the moderator band: This prominent trabeculation crossing the RV cavity is pathognomonic for the right ventricle 1

  • Check valve insertion levels: The tricuspid valve leaflets insert more apically than the mitral valve leaflets on the interventricular septum 1

  • Assess trabeculation pattern: Heavy trabeculations throughout the cavity indicate RV, while smooth endocardial surfaces suggest LV 1

In Short-Axis Views

  • RV wraps around LV: The RV appears as a crescent-shaped chamber wrapping around the circular LV in short-axis views 1

  • Identify the outflow tracts: The RV outflow tract extends superiorly toward the pulmonary valve, while the LV outflow tract leads to the aortic valve 1

Common Pitfalls to Avoid

  • Off-axis imaging: Ensure proper alignment in the apical four-chamber view to accurately assess the relative positions of the tricuspid and mitral valves 1

  • Confusing trabeculations with pathology: Normal RV trabeculations should not be mistaken for thrombus or masses; the moderator band is a normal structure 1

  • Assuming size equals identity: In severe RV dilation from volume or pressure overload, the RV may appear larger than the LV, but anatomical landmarks (moderator band, tricuspid valve position, trabeculations) remain reliable identifiers 1

  • Inadequate visualization: The entire RV including the apex and free wall must be contained in the imaging sector to properly assess its morphology 1

References

1
Guideline

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Dr.Oracle Medical Advisory Board & Editors, 2025

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