What are the normal interventricular septum (IVS) and posterior wall (PW) diameters on a 2D echocardiogram and above what values can left ventricular hypertrophy (LVH) be diagnosed?

Normal IVS and PW Diameter on 2D Echo and LVH Diagnostic Thresholds

The normal interventricular septum (IVS) and posterior wall (PW) thickness on 2D echocardiography is 0.6-0.9 cm in women and 0.6-1.0 cm in men, and left ventricular hypertrophy (LVH) should be diagnosed when left ventricular mass index exceeds 95 g/m² in women or 115 g/m² in men. 1

Normal Wall Thickness Values

The ASE/EACVI guidelines establish clear sex-specific reference ranges for wall thickness measurements 1:

• Women: IVS and PW thickness of 0.6-0.9 cm
• Men: IVS and PW thickness of 0.6-1.0 cm

These measurements should be obtained from the parasternal long-axis acoustic window at the level of the LV minor axis, approximately at the mitral valve leaflet tips, using 2D-guided M-mode or direct 2D measurement at the tissue-blood interface 1.

Diagnostic Criteria for LVH

LVH diagnosis should be based on calculated left ventricular mass (LVM) indexed to body surface area, not simply on wall thickness alone. 1 This is critical because wall thickness measurements alone miss a substantial proportion of patients with true LVH.

LVM Index Thresholds for LVH:

• Women: >95 g/m² (or >0.44 g/ht²·⁷) 1
• Men: >115 g/m² (or >0.48 g/ht²·⁷) 1

Calculation Formula:

The recommended formula for LVM calculation is 1:

LVM = 0.8 × {1.04[(LVIDd + PW + IVSd)³ - (LVIDd)³]} + 0.6 g

Where measurements are made at end-diastole using the actual tissue-blood interface 1.

Important Clinical Pitfalls

Why Wall Thickness Alone is Insufficient:

Research demonstrates that relying solely on wall thickness measurements (≥12 mm) identifies LVH in only 48% of patients with electrocardiographic LVH, whereas LVM calculation identifies 78-100% of cases 2. This occurs because:

• Eccentric hypertrophy presents with increased LV cavity size but normal wall thickness (33% of LVH cases) 2
• Volume overload states cause LVH without proportional wall thickening 1
• The cube formula magnifies small measurement errors, making direct thickness assessment unreliable 1

Geometric Classification:

Once LVH is diagnosed by LVM index, classify the pattern using relative wall thickness (RWT) 1:

RWT = (2 × PW thickness) / LV internal diameter at end-diastole

• Concentric LVH: LVM index elevated AND RWT ≥0.42 1
• Eccentric LVH: LVM index elevated AND RWT <0.42 1
• Concentric remodeling: Normal LVM index but RWT ≥0.42 1

Normal RWT range is 0.22-0.42 in women and 0.24-0.42 in men 1.

Measurement Technique Considerations

Use 2D-guided measurements at the actual tissue-blood interface rather than leading-edge to leading-edge convention. 1 The current ASE/EACVI guidelines emphasize that refinements in image processing allow direct visualization of the tissue-blood interface, providing more accurate measurements than older leading-edge techniques 1.

Critical Technical Points:

• Ensure the M-mode cursor or 2D measurement is perpendicular to the LV long axis 1
• If proper alignment cannot be achieved, use anatomical M-mode reconstructed from 2D images 1
• In asymmetric septal hypertrophy, linear methods overestimate mass at the base; use consistent methodology for serial assessments 1

Sex-Specific Differences

LVM values are systematically lower in women than men, even when indexed for body surface area 1. This sex difference persists across all indexing methods and must be accounted for when diagnosing LVH 1. Using male cutoffs for female patients will result in underdiagnosis of clinically significant LVH.