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Tissue Doppler echocardiography (TDE) is a
medical ultrasound Medical ultrasound includes diagnostic techniques (mainly imaging techniques) using ultrasound, as well as therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal body structures such as tendons, mu ...
technology, specifically a form of echocardiography that measures the velocity of the heart muscle ( myocardium) through the phases of one or more heartbeats by the Doppler effect (frequency shift) of the reflected
ultrasound Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies ...
. The technique is the same as for flow
Doppler echocardiography Doppler echocardiography is a procedure that uses Doppler ultrasonography to examine the heart. An echocardiogram uses high frequency sound waves to create an image of the heart while the use of Doppler technology allows determination of the spee ...
measuring flow velocities. Tissue signals, however, have higher amplitude and lower velocities, and the signals are extracted by using different filter and gain settings. The terms tissue Doppler imaging (TDI) and tissue velocity imaging (TVI) are usually synonymous with TDE because echocardiography is the main use of tissue Doppler. Like Doppler flow, tissue Doppler can be acquired both by spectral analysis ( spectral density estimation) as pulsed Doppler and by the autocorrelation technique as colour tissue Doppler (
duplex ultrasonography Doppler ultrasonography is medical ultrasonography that employs the Doppler effect to perform imaging of the movement of tissues and body fluids (usually blood), and their relative velocity to the probe. By calculating the frequency shift of a ...
). While pulsed Doppler only acquires the velocity at one point at a time, colour Doppler can acquire simultaneous pixel velocity values across the whole imaging field. Pulsed Doppler on the other hand, is more robust against noise, as peak values are measured on top of the spectrum, and are unaffected of the presence of clutter (stationary reverberation noise).


Pulsed tissue Doppler echocardiography

This has become a major echocardiographic tool for assessment of both systolic and diastolic ventricular function. However, as this is a spectral technique, ''it is important to realise that measurement of peak values is dependent on the width of the spectrum, which again is a function of gain setting''.


Clinical use

Pulsed wave spectral tissue Doppler has become a universal tool that is part of the general echocardiographic examination. Like any other echocardiographic measurement, measures by tissue Doppler should be interpreted in the context of the whole examination. The velocity curves are in general taken from the base of the mitral annulus at the insertion of the mitral leaflets, in the septal and lateral points of the four chamber view, and eventually the anterior and inferior points of the two-chamber views. For the right ventricle it is customary to use the lateral point of the tricuspid annulus only. Averaging peak velocities from the septal and lateral point has become common, although it has been shown that averaging all four points mentioned above, gives significantly less variability The method measures annular velocities to and from the probe during the heart cycle. Annular velocities summarize the longitudinal contraction of the ventricle during systole, and elongation during diastole. Peak velocities are commonly used.


Systolic function

Peak systolic annular velocity (S') of the left ventricle is as close to a contractility measure as you can get by imaging (bearing in mind that any imaging method only measures the result of fibre shortening, without measuring myocyte tension). S' has become a reliable measure of global function It shares the advantage of annular displacement, that it is reduced also in hypertrophic hearts with small ventricles and normal ejection fraction (HFNEF), which is often seen in
Hypertensive heart disease Hypertensive heart disease includes a number of complications of high blood pressure that affect the heart. While there are several definitions of hypertensive heart disease in the medical literature, the term is most widely used in the context of ...
, Hypertrophic cardiomyopathy and
Aortic stenosis Aortic stenosis (AS or AoS) is the narrowing of the exit of the left ventricle of the heart (where the aorta begins), such that problems result. It may occur at the aortic valve as well as above and below this level. It typically gets worse ov ...
. Likewise, peak tricuspid annular systolic velocity has become a measure of the right ventricular systolic function


Diastolic function

As the ventricle relaxes, the annulus moves towards the base of the heart, signifying the volume expansion of the ventricle. The peak mitral annular velocity during early filling, e' is a measure of left ventricular diastolic function, and has been shown to be relatively independent of left ventricular filling pressure. If there is impaired relaxation (
Diastolic dysfunction Heart failure with preserved ejection fraction (HFpEF) is a form of heart failure in which the ejection fraction – the percentage of the volume of blood ejected from the left ventricle with each heartbeat divided by the volume of blood when the l ...
), the e' velocity decreases. After the early relaxation, the ventricular myocardium is passive, the late velocity peak a' is a function of atrial contraction. The ratio between e' and a' is also a measure of diastolic function, in addition to the absolute values. During the two filling phases, there is early (E) and late (A)
blood flow Hemodynamics or haemodynamics are the dynamics of blood flow. The circulatory system is controlled by homeostatic mechanisms of autoregulation, just as hydraulic circuits are controlled by control systems. The hemodynamic response continuously m ...
from the atrium to the ventricle, corresponding to the annular velocity phases. The flow, is driven by the pressure difference between atrium and ventricle, this pressure difference is both a function of the pressure drop during early relaxation and the initial atrial pressure. In light diastolic dysfunction, the peak early mitral flow velocity E is reduced in proportion to the e', but if relaxation is so reduced that it causes increase in atrial pressure, E will increase again, while e', being less load dependent, remains low. Thus, the ratio E/e' is related to the atrial pressure, and can show increased filling pressure although with several reservations. In the right ventricle this is not an important principle, as the right atrial pressure is the same as central venous pressure which can easily be assessed from venous congestion.


Heart failure with preserved ejection fraction (HFPEF)

One of the main advantages of tissue Doppler is that diastolic and systolic function can be measured by the same tool. Before the advent of tissue Doppler, systolic function was usually assessed with
ejection fraction An ejection fraction (EF) is the volumetric fraction (or portion of the total) of fluid (usually blood) ejected from a chamber (usually the heart) with each contraction (or heartbeat). It can refer to the cardiac atrium, ventricle, gall bladder, ...
(EF), and diastolic function by mitral flow. This led to the concept of pure "
diastolic heart failure Heart failure with preserved ejection fraction (HFpEF) is a form of heart failure in which the ejection fraction – the percentage of the volume of blood ejected from the left ventricle with each heartbeat divided by the volume of blood when the ...
". However, In hypertrophic left ventricles with small cavity size, the systolic function is reduced although EF is not, as the EF is dependent on the relative wall thickness. This has led to the concept of "pure diastolic heart failure" being discarded. The preferred term is now heart failure with normal ejection fraction (HFNEF) or heart failure with preserved ejection fraction (HFPEF). This is common and is often seen in
hypertensive heart disease Hypertensive heart disease includes a number of complications of high blood pressure that affect the heart. While there are several definitions of hypertensive heart disease in the medical literature, the term is most widely used in the context of ...
, hypertrophic cardiomyopathy and
aortic stenosis Aortic stenosis (AS or AoS) is the narrowing of the exit of the left ventricle of the heart (where the aorta begins), such that problems result. It may occur at the aortic valve as well as above and below this level. It typically gets worse ov ...
, and may comprise as much as 50% of the total heart failure population. The prognosis of HFPEF is the same as for heart failure with dilated hearts.


Mitral valve prolapse (MVP)

Pulsed-wave tissue Doppler can be used as a way to evaluate the severeness of arrhythmic mitral valve prolapse, by looking at the peak in the middle of the systole, which looks similar to
Prussia Prussia, , Old Prussian: ''Prūsa'' or ''Prūsija'' was a German state on the southeast coast of the Baltic Sea. It formed the German Empire under Prussian rule when it united the German states in 1871. It was ''de facto'' dissolved by an ...
n Pickelhaube helmet, hence the name Pickelhaube spike. This is one of the risk markers for malignant arrhythmias in patients with myxomatous mitral valve disease (MMVD) and bileaflet mitral valve prolapse (BMVP). It's significant when exceeds 16 cm/s. The sudden systolic overload of which Pickelhaube spike is an expression can act as a trigger for the onset of ventricular arrhythmias.


Normal values and physiology

Normal gender and age related reference values For both S', e' and a' have been established in the large HUNT study, comprising 1266 subjects free of heart disease, hypertension and diabetes. This study also shows that both S' and e' values decline with age, while a' increases (fig). There is also a significant correlation between S' and e', also in healthy subjects, showing the connection between systolic and diastolic function. The e'/a' ratio becomes <1 about 60 years of age, which is similar to the E/A ratio of mitral flow. Women has slightly higher S' and e' velocities than men, although the difference disappears with age. The study also did show that velocities were highest in the lateral wall, and lowest in the septum. The E/e' was thus dependent on the site of e' measurement. The ratio was also age dependent.


Colour tissue Doppler

Unlike spectral Doppler, colour tissue Doppler samples velocities from all points of the sector, by shooting two pulses successively, and calculating the velocity from the phase shift between them by autocorrelation. The calculation is slightly different from the true Doppler effect, but the result becomes identical. This results in a single velocity value per sample volume. The result is a velocity field of (nearly) simultaneous velocity vectors towards the probe. The advantage of colour Doppler over spectral Doppler is that all velocities can be sampled simultaneously. The disadvantage is that if there is clutter noise (stationary reverberations), the stationary echoes will be integrated in the velocity calculation, resulting in an under estimate. As pulsed wave Doppler are displayed as a spectrum, the colour Doppler values will correspond to the mean of the spectrum (in the absence of clutter), giving slightly lower values. In the HUNT study, the difference in peak systolic values were about 1.5 cm/s. The local velocities are not the result of the local function, as segments are moved by the action of neighbouring segments. Thus the velocity differences
velocity gradient Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity is a ...
are the main measure of regional contraction, and has become the most important employment of colour tissue Doppler, in the method of
strain rate imaging Strain rate imaging is a method in echocardiography (medical ultrasound) for measuring regional or global deformation of the myocardium (heart muscle). The term "deformation" refers to the myocardium changing shape and dimensions during the cardi ...
.


References


Further reading

* * {{refend Medical ultrasonography Medical equipment Cardiac procedures