Tei Index (Myocardial Performance Index) in Echocardiography
The Tei index, also known as the Myocardial Performance Index (MPI), is a simple, reproducible echocardiographic parameter that integrates systolic and diastolic ventricular function into a single numerical value. It is widely used for both left and right ventricular functional assessment and is relatively independent of heart rate and ventricular geometry.
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What Is the Tei Index?
The Tei index reflects global ventricular performance by combining time intervals from Doppler echocardiography.
Formula:
\text{Tei Index (MPI)} = \frac{\text{IVCT} + \text{IVRT}}{\text{ET}}
Where:
IVCT = Isovolumic contraction time
IVRT = Isovolumic relaxation time
ET = Ejection time
A higher Tei index indicates worse ventricular function.
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How Is Tei Index Measured on Echocardiography?
1. Pulsed-Wave Doppler Method (Conventional)
Place PW Doppler at mitral inflow (LV) or tricuspid inflow (RV)
Measure interval ‘a’ = time from end of one inflow to onset of the next inflow
(includes IVCT + ET + IVRT)
Measure interval ‘b’ = ventricular ejection time from LVOT or RVOT
Calculate:
\text{Tei Index} = \frac{a - b}{b}
2. Tissue Doppler Imaging (TDI) Method
Place TDI sample at mitral annulus (LV) or tricuspid annulus (RV)
Measure:
IVCT
IVRT
ET directly from annular velocity waveform
Less affected by loading conditions and heart rate variability
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Normal Values
Ventricle Normal Tei Index
Left ventricle ≤ 0.40
Right ventricle ≤ 0.43
Values above these thresholds suggest global ventricular dysfunction.
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Clinical Applications
Heart failure (HFrEF and HFpEF)
Dilated cardiomyopathy
Ischemic heart disease
Pulmonary hypertension (RV MPI)
Congenital heart disease
Valvular heart disease
Post–myocardial infarction prognosis
The Tei index correlates with mortality, hospitalization, and adverse outcomes in multiple cardiac conditions.
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Advantages of Tei Index
Simple and quick to obtain
Combines systolic and diastolic function
Geometry-independent
Useful when EF is difficult to assess
Applicable to both LV and RV
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Limitations
Affected by significant valvular regurgitation
Less reliable in atrial fibrillation
Load-dependent in extreme preload/afterload states
Requires accurate Doppler alignment
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Key Echo Pearls
↑ Tei index = worse global ventricular function
Normal EF does not exclude abnormal MPI
Particularly useful in RV assessment, where EF estimation is challenging
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Take-Home Message
The Tei index (MPI) is a robust, Doppler-derived echocardiographic parameter that provides a global snapshot of ventricular performance, complementing conventional systolic and diastolic indices and enhancing risk stratification in everyday echo practice.

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