TV/TVM Tissue Doppler … Introducing Tissue Doppler What is it ?

TV/TVM

Tissue Doppler …

Introducing Tissue Doppler

What is it ?

TV/TVM

Definition of Tissue Doppler

Tissue Doppler is an emerging echocardiographic technique, which applies Doppler principles, to measure myocardial tissue velocities.


Tissue Doppler is a variation of conventional Doppler. Over the last ten years, TD has been proposed as a feasible and useful imaging tool, in order to assess the regional myocardial function.

Tissue Doppler is a variation of conventional Doppler. Over the last ten years, TD has been proposed as a feasible and useful imaging tool, in order to assess the regional myocardial function.

TV/TVM

Getting the gist


Technical basis

Different methodologies of TV/TVM

Clinical application findings

TD market analysis

We will focus on the technical aspects and the different methods of Tissue Doppler. We will also deal with the clinical application findings, in order to understand and to evaluate the actual TD market needs.

We will focus on the technical aspects and the different methods of Tissue Doppler. We will also deal with the clinical application findings, in order to understand and to evaluate the actual TD market needs.

TV/TVM

Technical Principles of TD


Blood Doppler Signal

• High velocities (100cm/s)

• Wide band (-fr/2, +fr/2)

• Low energies (TD/100)

Tissue Doppler Signal

• Low velocities (10cm/s) • Narrow band (-fr/8, +fr/8)

• High energies (BD*100)

Tissue Doppler

• No aliasing (-fr/8, +fr/8)

• Different filters (gain adjustator)

In current Doppler blood flow studies, the low Doppler shift frequencies, of high energy (40dB), generated by the myocardial wall motion, are purposely filtered out. Since these low Doppler shift frequencies are produced by contracting myocardium, they are expected to contain potential information for the assessment of myocardial properties. Early description of this technique have already suggested its potential to evaluate both systolic and diastolic myocardial function.

In current Doppler blood flow studies, the low Doppler shift frequencies, of high energy (40dB), generated by the myocardial wall motion, are purposely filtered out. Since these low Doppler shift frequencies are produced by contracting myocardium, they are expected to contain potential information for the assessment of myocardial properties. Early description of this technique have already suggested its potential to evaluate both systolic and diastolic myocardial function.

TV/TVM

Tissue Doppler modalities

Tissue Velocity (TV)

Quantitative Assessment

Tissue Velocity Mapping (TVM)

Semi-Quantitative Assessment

Qualitative Assessment

Mono-dimensional Bi-dimensional

The velocity of moving tissues can be studied with pulsed wave tissue Doppler sampling, which displays the velocity of a selected myocardial region against time.

In addition, the velocities can be calculated with time velocity maps and displayed as color coded velocity maps, in either M-mode or two-dimensional format.

The velocity of moving tissues can be studied with pulsed wave tissue Doppler sampling, which displays the velocity of a selected myocardial region against time.

In addition, the velocities can be calculated with time velocity maps and displayed as color coded velocity maps, in either M-mode or two-dimensional format.

TV/TVM Tissue Doppler modalities

* The overall function of the left ventricle depends on a normal contraction of the longitudinally and circumferentially orientated fibers. * Quantification of the LV function, in the longitudinal axis, may be clinically relevant since the contraction in this direction is mainly due to subendocardial fibers. In particular, one can expect that in case of ischemia, which specifically alters subendocardial layers, first abnormalities of wall motion will appear in the longitudinal axis. * As the apex of the heart remain remarkably stationary, long axis changes are reflected in movements of the base of the heart.

* The overall function of the left ventricle depends on a normal contraction of the longitudinally and circumferentially orientated fibers. * Quantification of the LV function, in the longitudinal axis, may be clinically relevant since the contraction in this direction is mainly due to subendocardial fibers. In particular, one can expect that in case of ischemia, which specifically alters subendocardial layers, first abnormalities of wall motion will appear in the longitudinal axis. * As the apex of the heart remain remarkably stationary, long axis changes are reflected in movements of the base of the heart.

What are we actually measuring ?

Epicardial and subendocardial fibers

Longitudinally orientated fibers Longitudinal function

Intramiocardial fibers

Circumferentially orientated fibers

Circumferential function



Quantitative Assessment of regional myocardial function

Sample Volume positioning (Longitudinal dynamics)

Locate the sample volume at the lateralmargin and at the common septal margin of the tricuspid and mitral anuli.

“S”

2.5 ± 1.2 cm/s

7.5 ± 1.9 cm/s

“A”

5.4 ± 2.3 cm/s

6.3 ± 2.1 cm/s

“E”

10.8 ± 3.1 cm/s

14.6 ± 3.6 cm/s

The PW-TD pattern can be divided into two parts, systolic and diastolic, from which several measurements can be obtained. The systolic phase is characterized by a positive wave “S” preceded by the time taken from regional isovolumic contraction (RIVCT). The diastolic phase, which is more complex, is composed of 4 periods. The regional isovolumic relaxation (RIVRT). The rapid filling period, characterized by a negative wave “E”. The diastasis, which doesn’t exhibit any movements, and the filling period due to atrial contraction, represented by a second negative wave “A”.

The PW-TD pattern can be divided into two parts, systolic and diastolic, from which several measurements can be obtained. The systolic phase is characterized by a positive wave “S” preceded by the time taken from regional isovolumic contraction (RIVCT). The diastolic phase, which is more complex, is composed of 4 periods. The regional isovolumic relaxation (RIVRT). The rapid filling period, characterized by a negative wave “E”. The diastasis, which doesn’t exhibit any movements, and the filling period due to atrial contraction, represented by a second negative wave “A”.

TV/TVM



Quantitative Assessment of regional myocardial function

Advantages :

• high temporal resolution • v [cm/s] , a [cm/s2] • rapid quantification

Inconveniences :

• manually mapping • no simultaneous recording• low wall filter and low gain setting

Pulsed-wave-TDI provides real-time

Doppler signals with high temporal

resolution, but allows only step by step

evaluation of single sampling points of

interest. Therefore, reproducibility may be

lower than for color-Doppler-TDI.

Pulsed TD permits to obtain high quality Doppler signals, due to its high temporal resolution. To measure, in addition to velocity, mean and instantaneous acceleration and to obtain rapid quantification of these magnitudes. However, pulsed TD suffers from the following limitations. The need for manually performed mapping, the impossibility of simultaneous recording of different ventricular wall segments. Although pulsed Doppler signals can be obtained with all available commercialized US machines, a low wall filter and low gain settings are needed to obtain high quality signals.

Pulsed TD permits to obtain high quality Doppler signals, due to its high temporal resolution. To measure, in addition to velocity, mean and instantaneous acceleration and to obtain rapid quantification of these magnitudes. However, pulsed TD suffers from the following limitations. The need for manually performed mapping, the impossibility of simultaneous recording of different ventricular wall segments. Although pulsed Doppler signals can be obtained with all available commercialized US machines, a low wall filter and low gain settings are needed to obtain high quality signals.

TV/TVM



Semi-Quantitative Assessment of regional myocardial function

M-mode color TD of the myocardiumallows us to superimpose wall motion velocity on the mono-dimensional echocardiographic imaging, by velocity color coding.

M-mode color TD of the myocardium allows us to superimpose wall motion velocity on the mono-dimensional echocardiographic imaging, by velocity color coding. Depending on the orientation of the cardiac structures relative to the US beam, the velocity signals appear red or blue according to movement of the myocardium towards or away from the transducer, respectively. Moreover, different color coding scales reflect different velocities: low velocities are coded with dark colors, while high velocities are coded with bright colors.

The M-mode color TD from the parasternal and apical views, allows the analysis of contraction and relaxation of circumferential (intra-myocardial) and longitudinal (sub-endocardial) fibers, respectively.

M-mode color TD of the myocardium allows us to superimpose wall motion velocity on the mono-dimensional echocardiographic imaging, by velocity color coding. Depending on the orientation of the cardiac structures relative to the US beam, the velocity signals appear red or blue according to movement of the myocardium towards or away from the transducer, respectively. Moreover, different color coding scales reflect different velocities: low velocities are coded with dark colors, while high velocities are coded with bright colors.

The M-mode color TD from the parasternal and apical views, allows the analysis of contraction and relaxation of circumferential (intra-myocardial) and longitudinal (sub-endocardial) fibers, respectively.

TV/TVM



Advantages :

• high spatio-temporal resolution• Δt [s]

Inconveniences :

• single line• low wall filter and low gain setting

Mono-dimensional TVM

M-mode color-coded TD is characterized by a high spatio-temporal resolution, but sampling is performed only on a single line. Moreover, it requires specific modification of the conventional US scanner.

M-mode color-coded TD is characterized by a high spatio-temporal resolution, but sampling is performed only on a single line. Moreover, it requires specific modification of the conventional US scanner.

.


Qualitative Assessment of regional myocardial function


Like in the Color Doppler application,

in TD the different velocities are

correlated with a preset colour

scheme and, super-imposed on the

2-dimensional image displayed as

colour flow on the monitor.

Blood flow towards the transducer is

colour-coded in red shades while

blood flow away from the transducer

is colour coded in shades of blue.

Color TD of the myocardium allows us to superimpose wall motion velocity on the two-dimensional echocardiographic imaging, by velocity color coding. Depending on the orientation of the cardiac structures relative to the US beam, the velocity signals appear red or blue according to movement of the myocardium towards or away from the transducer, respectively.

Color TD of the myocardium allows us to superimpose wall motion velocity on the two-dimensional echocardiographic imaging, by velocity color coding. Depending on the orientation of the cardiac structures relative to the US beam, the velocity signals appear red or blue according to movement of the myocardium towards or away from the transducer, respectively.

TV/TVM



Advantages :

• rapid visual qualitative assessment • high spatial resolution• analysis of simultaneous regions

Inconveniences :

• weak temporal resolution• low wall filter and low gain setting

Bi-dimensional TVMTwo-dimensional color TD allows a rapid visual qualitative assessment of the dynamics of the wall, provides a good spatial resolution that permits differentiation of the velocity profiles between subendocardial and subepicardial layers and allows us to analyze simultaneously various myocardium regions. However it is limited by its poor temporal resolution which varies according to the system used and ranges from 100 ms in first generation scanners, to 10 ms in the new fully-digital systems. Moreover, it requires specific modification of the conventional US scanner.

Two-dimensional color TD allows a rapid visual qualitative assessment of the dynamics of the wall, provides a good spatial resolution that permits differentiation of the velocity profiles between subendocardial and subepicardial layers and allows us to analyze simultaneously various myocardium regions. However it is limited by its poor temporal resolution which varies according to the system used and ranges from 100 ms in first generation scanners, to 10 ms in the new fully-digital systems. Moreover, it requires specific modification of the conventional US scanner.

TV/TVM

Clinical Applications :TTE Transthoracic approach

Hospitals

Sport Medicine

Research

•Diastolic Function

•Myocardial ischemia

•Cardiomiopathy

TV/TVM

Clinical Applications : TEE Transesofageal approach

Clinical Applications

•Multisite stimulation in refractory heart failure

•Wolff-Parkinson-White syndrome

•Left atrial appendage

Electrophysiology department

TV/TVM

The…… End……

TV/TVM Tissue Doppler … Introducing Tissue Doppler What is it ?

Documents

Transcript of TV/TVM Tissue Doppler … Introducing Tissue Doppler What is it ?