E/e' ratio
Pronunciation: E over e-prime
An echocardiographic parameter calculated by dividing mitral E velocity by tissue Doppler e' velocity to estimate left atrial pressure.
Full Definition
The E/e' ratio (E over e-prime ratio) is a dimensionless echocardiographic index used to estimate left ventricular filling pressures and diagnose diastolic dysfunction. The E velocity represents peak early diastolic mitral inflow velocity measured by pulsed-wave Doppler, while e' (e-prime) represents peak early diastolic mitral annular velocity measured by tissue Doppler imaging. Normal E/e' ratio is typically less than 10, with values above 14 suggesting elevated filling pressures. This parameter is less preload-dependent than traditional mitral inflow patterns and provides valuable hemodynamic information in patients with heart failure, particularly those with preserved ejection fraction.
Usage
Usage note: Use forward slash notation (E/e'). The apostrophe in e' is essential to distinguish from mitral E velocity. Avoid confusion with E/A ratio.
In Context
- "The E/e' ratio was elevated at 16, suggesting increased filling pressures." — Echocardiography report
- "Diastolic function assessment revealed normal E/e' ratio of 8." — Follow-up echo report