Tissue Doppler imaging (TDI) is an echocardiographic technique that uses Doppler principles to measure the velocity of displacement of the annulus (mitral, septal and tricuspid) and reflects the function of longitudinal fibers (mitral – LV function; Septal – global function and tricuspid annulus – RV function). Like many other parameters, it depends upon angle of insonation.

The cardiac cycle is represented by 3 waveforms:

1) S’, systolic myocardial velocity above the baseline as the annulus descends toward the apex;

(2) E’, early diastolic myocardial relaxation velocity below the baseline as the annulus ascends away from the apex;

(3) A’, myocardial velocity associated with atrial contraction

Systolic myocardial velocity (S’) at the lateral mitral annulus is a measure of longitudinal systolic function of LV and is correlated with measurements of LVEF, value < 6cm/sec is correlated with LV impairment function. For RV normal value is > 10cm/sec.

In normal subjects E’ increases as transmitral gradient increases with exertion or increased preload, whereas in patients with impaired myocardial relaxation E’ is reduced at baseline and does not increase as much as in normal subjects with increased preload. Lateral annulus early diastolic velocity is usually higher than septal annulus E’. Decreased E’ is one of the earliest markers for diastolic dysfunction and is present in all stages of diastolic dysfunction. Because E’ velocity remains reduced and mitral E velocity  in mitral flow increases with higher filling pressure, the ratio between transmitral E and E’ (E/E’), correlates well with LV filling pressure or pulmonary capillary wedge pressure (PCWP) in adults (ratio E/E’ > 15 is indicative of increased left heart filling pressure in adults), not demonstrated in children. Adult Guidelines do not readily translate to children.

Figure: E mitral 86cm/sec, E’ 14cm/sec, ratio E/E’ = 86/ 14= 6 (normal ratio)