E-point septal separation (EPSS)

 

E-point septal separation (EPSS)

E-point septal separation (EPSS) is a simple M-mode echocardiographic measurement used to assess left ventricular (LV) systolic function.

🔹 Definition

▪︎ EPSS = distance (in mm) between:

○ The E-point (maximal early diastolic opening of the anterior mitral valve leaflet)

○ And the interventricular septum

▪︎ Measured in parasternal long-axis view (PLAX) using M-mode.

🔹 Normal vs Abnormal

▪︎ Normal: ≤ 5–7 mm

▪︎ Mildly increased: 7–10 mm

▪︎ Severely increased: > 10 mm

🔹 Clinical Significance

👉 EPSS is inversely related to LV ejection fraction (EF)

▪︎ Small EPSS → normal EF

▪︎ Large EPSS → reduced EF

EPSS – Key Equation (Clinical Estimation of EF)

👉 LVEF (%) ≈ 75.5 − (2.5 × EPSS in mm)

🔹 Example

EPSS = 10 mm

→ EF ≈ 75.5 − (2.5 × 10)

→ EF ≈ 50%

EPSS on Echocardiography

E-Point Septal Separation

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Definition

EPSS (E-Point Septal Separation) is the minimal distance between the anterior mitral valve leaflet (E-point) and the interventricular septum during early diastole measured on M-mode echocardiography.

It is a simple surrogate marker of left ventricular systolic function.

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How EPSS is Measured

Step-by-step technique

1. Obtain parasternal long axis (PLAX) view.

2. Activate M-mode cursor through the tips of the mitral valve leaflets.

3. Identify the E-wave (maximal anterior motion of the anterior mitral leaflet).

4. Measure the shortest distance between the E-point and interventricular septum.

Measurement is taken in millimeters (mm).

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Normal Values

EPSS Interpretation

< 5 mm Normal LV systolic function

5–7 mm Borderline

> 7 mm Suggests LV systolic dysfunction

> 10 mm Strongly suggests severe LV dysfunction

Approximate correlation:

EPSS < 5 mm → LVEF usually > 55%

EPSS > 7 mm → LVEF usually < 50%

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Why EPSS Increases

When LV systolic function is reduced, the ventricle dilates and contractility decreases.

This causes:

• Reduced anterior motion of the mitral leaflet

• Increased distance between mitral leaflet and septum

Therefore EPSS becomes larger.

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Clinical Uses

1. Rapid estimation of LV systolic function

2. Useful in emergency or bedside echocardiography

3. Helpful when endocardial borders are poorly visualized

4. Screening tool in heart failure evaluation

Common settings:

Dilated cardiomyopathy

Ischemic cardiomyopathy

Acute myocardial infarction

Shock assessment in ICU

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Limitations of EPSS

EPSS becomes unreliable in several conditions:

• Mitral stenosis

• Mitral valve prosthesis

• Significant mitral regurgitation

• Aortic regurgitation

• Septal hypertrophy (HCM)

• Regional wall motion abnormalities

In these situations LVEF should be measured using Simpson biplane method.

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EPSS vs LVEF Relationship

A commonly used approximation:

LVEF ≈ 75.5 − (2.5 × EPSS in mm)

Example:

EPSS = 10 mm

Estimated EF ≈ 50%

This formula provides only a rough estimation.

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Key Practical Point

EPSS is not a replacement for formal LVEF measurement, but it is a quick bedside indicator of LV systolic dysfunction, especially in focused cardiac ultrasound (FoCUS).

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Summary

EPSS = distance between mitral valve E-point and interventricular septum

Measured using M-mode in PLAX view

<5 mm normal, >7 mm suggests LV dysfunction

Simple, rapid indicator of reduced LVEF

Limited by valvular disease and septal abnormalities

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