Left-ventricular geometry describes how myocardial mass and wall-thickness pattern relate to cavity size. It is not synonymous with hypertrophy, and it cannot be classified from septal thickness alone.
The standard framework combines LV mass index with relative wall thickness to identify four patterns: normal geometry, concentric remodelling, concentric hypertrophy, and eccentric hypertrophy.
Step 1: acquire valid linear inputs
LV mass calculations are highly sensitive to the parasternal long-axis measurements used in the equation. Measure at end-diastole, perpendicular to the LV long axis, near the mitral-leaflet tips. Avoid chordae, papillary muscle, RV trabeculation, and oblique sections.
- Interventricular septal thickness in diastole
- LV internal diameter in diastole
- Posterior-wall thickness in diastole
Because the dimensions are cubed, small errors can substantially alter calculated mass.
Step 2: calculate LV mass
The commonly used ASE-corrected cube formula models the LV as a prolate ellipsoid and subtracts the cavity volume from the total volume enclosed by the epicardial surface.
The equation is practical and well established but assumes a relationship between the measured basal dimensions and the entire ventricle. It is less representative when hypertrophy is asymmetric, the LV is distorted, or wall thickening is localized.
Step 3: index mass
LV mass is commonly indexed to body-surface area. The 2015 ASE/EACVI upper reference limits are approximately 115 g/m² for men and 95 g/m² for women. Laboratories should use their adopted current reference standard.
Indexing improves comparison across body sizes but requires judgment in severe obesity and unusual body habitus.
Step 4: calculate relative wall thickness
A relative wall thickness above approximately 0.42 supports a concentric pattern. RWT does not indicate whether LV mass is increased; it describes the relationship between posterior-wall thickness and cavity diameter.
The four geometry patterns
| LV mass index | RWT | Geometry | Concept |
|---|---|---|---|
| Normal | Normal | Normal geometry | Mass and wall-thickness relationship are within reference limits |
| Normal | Increased | Concentric remodelling | Walls are relatively thick for cavity size without increased total mass |
| Increased | Increased | Concentric hypertrophy | Increased mass with a concentric wall-thickness pattern |
| Increased | Normal | Eccentric hypertrophy | Increased mass associated with a relatively larger cavity |
Normal geometry
Normal geometry does not mean every other aspect of LV structure and function is normal. Regional hypertrophy, apical abnormalities, scar, wall-motion abnormalities, and diastolic dysfunction may still be present.
Concentric remodelling
Concentric remodelling describes increased RWT with normal LV mass index. It may reflect pressure loading, ageing, or other adaptation. The classification should not be called LV hypertrophy because mass is not elevated.
Concentric hypertrophy
Concentric hypertrophy combines increased LV mass index and increased RWT. It is commonly associated with chronic pressure loading, including hypertension and aortic stenosis, but the geometry pattern alone does not establish cause.
Eccentric hypertrophy
Eccentric hypertrophy combines increased LV mass with a normal RWT. It can occur with chronic volume loading or dilated remodelling. The term describes geometry rather than a specific diagnosis.
Asymmetric hypertrophy requires a different mindset
The cube formula assumes that basal linear measurements represent the whole LV. In hypertrophic cardiomyopathy or other localized hypertrophy, a single septal and posterior-wall measurement may underestimate or misrepresent total myocardial distribution.
- Systematically measure maximal wall thickness in multiple segments.
- Inspect basal, mid, and apical levels.
- Use contrast when endocardial definition limits assessment.
- Integrate CMR when clinically indicated.
- Do not use RWT to describe the distribution of asymmetric HCM.
Linear LV mass assumes a reasonably symmetric ventricle. When hypertrophy is focal, asymmetric, or apical, use a systematic segmental 2D assessment and integrate 3D echocardiography or CMR when clinically appropriate.
Common classification errors
Calling thick walls “concentric hypertrophy” without mass
Concentric hypertrophy requires increased LV mass index and increased RWT. Wall thickness alone is insufficient.
Using the septum twice in the RWT formula
The conventional formula uses twice the posterior-wall thickness divided by LVIDd. Laboratories should follow their standardized software and guideline method.
Measuring in systole
Wall thickness and cavity diameter change during systole. The LV mass inputs must be measured at end-diastole.
Comparing different methods
Linear cube, 2D area-length, 3D, CT, and CMR mass values are not necessarily interchangeable.
A major change in LV mass or geometry should prompt review of raw images, measurement plane, body-size indexing, and blood pressure before biological change is assumed.
Integrating geometry with physiology
Geometry is one component of the report. Interpret it with LV size, EF, strain when available, diastolic variables, LA volume, valve disease, blood pressure, and clinical history. A patient with concentric remodelling and preserved EF may still have important diastolic dysfunction. A patient with eccentric hypertrophy may have preserved or reduced systolic function depending on the underlying process.
Knowledge check
1. Increased RWT with normal LV mass index represents:
Answer: Concentric remodelling.
2. Why can one millimetre materially alter LV mass?
Answer: The linear dimensions are cubed in the equation.
3. Can RWT classify asymmetric septal hypertrophy?
Answer: No. RWT describes a global concentric relationship and does not characterize localized hypertrophy.