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6 Transthoracic M-Mode Echocardiography
65
used to calculate time intervals such as isovolumic relaxation or contraction time.
The benets of m-mode, described above,
make it an advantageous mode for specic applications, which will be described below. See Box
6.2 for a list of m-mode parameters used in a com-
prehensive TTE and in specic clinical situations.
Box 6.2 M-Mode Uses
1. For a comprehensive TTE: Aortic and
mitral valve in PLAX, TAPSE, IVC
with respiratory variation.
2. Specic situations:
(a) LV-FS, EPSS, and MAPSE: Use as
an adjunct for the LV systolic function with difcult windows.
(b) RVOT-FS: Use as an adjunct for the
RV systolic function with difcult
windows.
(c) Velocity of propagation (Vp): Use
when a (relatively) load- independent
metric of the diastolic function is
needed.
(d) MV in PLAX looking for SAM:
Assess if there is clinical concern
for outow obstruction.
(e) RV cavity diastolic collapse: Use
when there is pericardial uid and
clinical concern for tamponade.
eters, including LV fractional shortening, E-point
septal separation, and the mitral annular plane
systolic excursion (MAPSE), all correlate with
the LV ejection fraction.
Diastolic LV function, or the lling of the left
ventricle, is a complex phenomenon. Active and
passive LV relaxation as well as left atrial pressure
dictate how the LV lls. One limitation of current
echocardiographic diastolic function guidelines
[3] is that many patients are deemed to have “indeterminate diastolic function.” Additional echocardiogram parameters can be used to supplement the
understanding of diastolic function in those indeterminate cases. One of these parameters is the
propagation velocity (V
), which is acquired using
p
color m-mode through the mitral valve. Vp
describes how rapidly blood ow propagates from
the mitral valve to the LV apex and is thought to be
relatively load independent. This means that it primarily describes the relaxation of the ventricle
independent of preload and afterload [4]. Multiple
methods have been described for acquiring Vp and
studies have correlated it with various diastology
metrics. One proposed “normal” cutoff is 45m/s,
with values below that velocity representing an
abnormal diastolic function [5] (Fig.6.2 showing
Vp measurement).
Right Ventricular (RV) Systolic Function
M-Mode Echocardiography
Left Ventricular (LV) Function
The assessment of LV systolic function is one of
the most common reasons to perform echocardiography. Suboptimal imaging is extremely
common in the critically ill due to factors such as
difcult patient positioning, patient inability to
cooperate, and medical devices that interrupt
access to the chest. Frequently, a complete echocardiogram and assessment of LV function are
impossible. If only limited views are available,
m-mode may be used to supplement the evaluation of the LV function. M-mode-derived param-
Unlike the bullet-shaped LV, the RV is not a typical geometric structure. This makes quantication of RV systolic function more difcult.
Tricuspid annular plane systolic excursion
(TAPSE) is a commonly used and quantiable
metric of RV function [6]. TAPSE uses m-mode
to assess the vertical motion of the lateral tricuspid annulus and provides information about the
function of longitudinal RV myocardiocytes.
Right ventricular outow tract fractional shortening (RVOT FS), which is measured using m-mode
in either the parasternal long- or short-axis, is an
emerging metric to evaluate RV systolic function.
RVOT FS correlates well with the RV function
when compared to cardiac MR images [7]
(Fig.6.3 showing TAPSE and RVOT FS).
66
Fig. 6.2 Velocity of
propagation (Vp). Color
m-mode is obtained
through the mitral valve
from an apical
four-chamber view. The
Nyquist limit is set at
75% of the E velocity,
the sweep speed is
typically set at
100mm/s, and the V
p
slope is measured at the
aliasing velocity (black
dotted line)
B. Burk
Fig. 6.3 M-mode indicators of the right heart
function. TAPSE uses m-mode to show the vertical
displacement of the lateral tricuspid annulus. A
value of 17mm or greater is normal. Panel (a)
shows a reduced TAPSE suggesting reduced RV
function. Panel (b) shows the measurements for
RVOT fractional shortening in a patient with severe
pulmonary hypertension. This m-mode tracing was
obtained from the PLAX and the RV internal
diameters are measured at the end systole and end
diastole (white arrows)
a
b
6 Transthoracic M-Mode Echocardiography
67
Cardiac Valves
Until the advent of 2D and Doppler echocardiography, m-mode was relied on for the assessment
of valvular function [8]. In the modern era, 2D
and Doppler echocardiography have largely
replaced m-mode for the evaluation of cardiac
valves. However, the recognition of normal
m-mode patterns allows the echocardiographer to
notice when an abnormal pattern is present. This
can alert them to the need for a more detailed
valve assessment.
M-mode is commonly performed on the aortic
and mitral valves in the parasternal long-axis.
When it is visualized well, m-mode may also be
performed on the pulmonic valve in the parasternal short or long axis. Tricuspid valve m-mode is
uncommon.
To perform m-mode of the mitral valve, the
echocardiographer places the m-mode cursor
through the mitral valve in a parasternal longaxis view. Alternatively, one may utilize the parasternal short-axis at the mitral valve level, or the
“sh mouth” view. Ideally, the m-mode cursor
traverses both the anterior and posterior leaets
of the mitral valve. When normal sinus rhythm is
present, the E and A waves are identied by the
anterior motion of the anterior mitral valve leaflet. These represent the opening of the valve leaflet during early diastolic lling (E) and the atrial
kick (A). There may be a at space between the E
and A waves, which represents diastasis, the midportion of diastole during which mitral ow is
diminished or absent. During systole, the mitral
valve remains passive or moves slightly anteriorly due to ventricular movement (Fig.6.4 showing normal m-mode and m-mode with mitral
stenosis).
Aortic valve m-mode is also obtained from the
parasternal long-axis view. The right coronary
cusp is seen anteriorly and either the left or the
noncoronary cusp are seen posteriorly. The
sonographer places the m-mode cursor through
both visualized leaets and m-mode is activated.
Coaptation of the valve leaets is seen during
diastole and during systole the aortic valve leaflets open creating the appearance of rectangles
on a string (Fig. 6.5 shows a normal AoV
a
b
Fig. 6.4 Mitral valve m-mode. Panel (a) shows a normal
E and A wave (white arrows). Panel (b) shows the m-mode
appearance of severe mitral stenosis. If abnormalities are
noted, such as thickened valves or perturbations in the
normal E and A pattern, the valve should be evaluated
more fully
m-mode). Abnormal coaptation and opening are
indicators of valvular dysfunction and should
prompt additional evaluation of the valve.
The pulmonic valve is more difcult to see on
transthoracic echo. If windows allow for it, the
pulmonic valve may be seen either in the parasternal long or short axis. From a standard parasternal long axis, tilt the probe so that the
ultrasound beam aims more cranially and to the
patient’s left, which allows visualization of the
pulmonic valve and main pulmonary artery.
From the parasternal short axis at the level of the
aortic valve, the pulmonic valve may be seen in
the 2 o’clock position. Small probe adjustments
are often required from this view to optimize the
visualization of the pulmonic valve. In a normal
heart, the right atrial contraction causes a rise in
68
Fig. 6.5 Normal
m-mode through the
aortic valve with the
appearance of rectangles
(valve open) on a string
(valve closed). Note the
thin leaets that open
and close quickly.
Thickened leaets or
abnormalities in opening
or closing suggest the
need for further
investigation of the
valve
B. Burk
right ventricular pressure resulting in a small
posterior displacement of the pulmonic valve
(A), followed by a larger posterior movement
that represents valve opening. This typical pattern may be disrupted in abnormal physiologic
states, such as pulmonary hypertension or pulmonic stenosis.
Outow Obstruction
Outow obstruction is a relatively frequent
occurrence in the critically ill. Improper management can lead to profound shock and death.
Thus, identication with echocardiography is
essential. In the latter stages of outow obstruction, high- velocity ow in the left ventricular
outow tract causes a Bernoulli effect that pulls
open the anterior mitral leaet during systole.
This mitral opening further obstructs blood ow
in the outow tract and results in signicant
mitral regurgitation. This phenomenon is termed
“systolic anterior motion of the mitral valve,” or
SAM. Mitral valve motion is very rapid and
these patients are typically tachycardic, so SAM
is difcult to identify with the unaided human
eye watching a 2D cine loop. M-mode can be
essential in identifying SAM because of its high
temporal resolution. As compared to the usual
mitral valve m-mode tracing, when SAM is present, anterior movement of the mitral valve is
seen during systole in addition to the E and A
waves (Fig.6.6).
Pericardial Tamponade
Pericardial tamponade occurs when pressure in
the pericardium exceeds pressure in the right
heart, causing the right heart chambers to collapse during lling. This impaired lling results
in poor cardiac output. RV collapse is seen on
the echocardiogram during the latter stages of
tamponade. The RV appropriately moves inward
during systole due to contraction, therefore it
can be difcult to differentiate this appropriate
contraction from an inappropriate diastolic collapse when viewing a 2D cine loop. M-mode
shows the timing of ventricular inward movement during the cardiac cycle (Fig.6.7 showing
RV collapse in diastole). M-mode images
through the pericardial effusion and RV may be
obtained from either the parasternal long axis,
parasternal short axis, or the subcostal fourchamber view with the m-mode cursor perpendicular to the long axis of the RV.
6 Transthoracic M-Mode Echocardiography
Fig. 6.6 Systolic
anterior motion of the
mitral valve (SAM,
white arrow) due to
hypertrophic
cardiomyopathy.
Compare this to the
normal mitral valve
movement in Fig.6.4,
panel (a)
Fig. 6.7 RV-free wall
collapse (white arrow)
during diastole due to
tamponade. This image
was obtained in the
parasternal long axis,
but a parasternal short
axis or a subcostal view
may also be used
69
Inferior Vena Cava (IVC) Collapsibility
Analysis of the IVC is a common application of
point-of-care echocardiography in the critically
ill. In the appropriate clinical context, uid
responsiveness may be predicted by vena cava
collapse. RA pressure can be estimated using a
combination of the IVC size and collapsibility
[9]. Respirophasic variation in IVC diameter
can be assessed using m-mode either in the IVC
long axis or short axis. One drawback of the
long-axis view is that during inhalation, the
movement of the diaphragm may cause the IVC
to move out of the plane of the ultrasound
beam, thus invalidating measurements
70
due
End-exhalation Inhalation
Short axis
Short axis
Long axis
Long axis
B. Burk
m-mode
cursor
True IVC Collapse
Short axis
False “IVC collapse”
to probe movement
Fig. 6.8 True IVC collapse versus the false appearance
of IVC collapse in the long axis due to lateral probe movement during inhalation. This problem can be solved using
Long axis
(Fig.6.8). This problem may be overcome by
switching to a short-axis view of the vena cava.
The m-mode cursor is seen traversing the center
of the IVC in the scout image, so the sonographer can ensure that respiratory movement does
not affect the position of the ultrasound beam in
the IVC.
In the long-axis view, the echocardiographer
places the m-mode cursor just upstream of the
hepatic vein junction with the IVC.Care must be
taken to ensure that the m-mode cursor is as perpendicular to the long axis of the IVC as possible.
In the short-axis view, a similar location should be
selected, although it can be more challenging to
identify the hepatic inow in the short axis. Ideally,
a respirometer tracing is used to identify inspiration, but this is often not possible in the point-ofcare setting. The m-mode tracing should be frozen
and captured once a full respiratory cycle has
occurred. The expiratory diameter is measured at
end-exhalation. There is no consensus on when to
measure during inhalation, but the smallest diameter during the inhale is frequently used.
Summary Points
• M-mode has two major advantages over 2D
imaging: (1) high temporal resolution and (2)
Short axis
the short axis as the scout view so the sonographer can
ensure the m-mode cursor stays in the middle of the
vessel
Long axis
the ability to show cardiac movement over the
respiratory cycle.
• These benets put m-mode at an advantage in
specic clinical situations to show fastmoving and respirophasic phenomena.
• While 2D imaging is the workhorse of echocardiography, m-mode is still a key tool that
the echocardiographer must be familiar with.
References
1. Armstrong WF, Ryan T. Feigenbaum’s echocardiography. 8th ed. Philadelphia: Wolters Kluwer;
2019.
2. Carerj S, Micari A, Trono A, Giordano G, Cerrito M,
Zito C, etal. Anatomical M-mode: an old-new technique. Echocardiography. 2003;20(4):357–61.
3. Nagueh SF, Smiseth OA, Appleton CP, Byrd BF 3rd,
Dokainish H, Edvardsen T, et al. Recommendations
for the evaluation of left ventricular diastolic function
by echocardiography: an update from the American
Society of Echocardiography and the European
Association of Cardiovascular Imaging. J Am Soc
Echocardiogr. 2016;29(4):277–314.
4. Garcia MJ, Smedira NG, Greenberg NL, Main M,
Firstenberg MS, Odabashian J, etal. Color M-mode
Doppler ow propagation velocity is a preload
insensitive index of left ventricular relaxation: animal and human validation. J Am Coll Cardiol.
2000;35(1):201–8.
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5. De Boeck BW, Oh JK, Vandervoort PM, Vierendeels
JA, van der Aa RP, Cramer MJ.Colour M-mode velocity propagation: a glance at intra-ventricular pressure
gradients and early diastolic ventricular performance.
Eur J Heart Fail. 2005;7(1):19–28.
6. Kaul S, Tei C, Hopkins JM, Shah PM.Assessment
of right ventricular function using two-dimensional
echocardiography. Am Heart J. 1984;107(3):526–31.
7. Srinivasan A, Kim J, Khalique O, Geevarghese A,
Rusli M, Shah T, etal. Echocardiographic linear fractional shortening for quantication of right ventricular
systolic function—a cardiac magnetic resonance validation study. Echocardiography. 2017;34(3):348–58.
8. Chang S. M-mode echocardiographic techniques
and pattern recognition. London: Lea & Febiger;
1976.
9. Rudski LG, Lai WW, Afilalo J, Hua L,
Handschumacher MD, Chandrasekaran K, et al.
Guidelines for the echocardiographic assessment of the right heart in adults: a report from the
American Society of Echocardiography endorsed
by the European Association of Echocardiography,
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Echocardiography. J Am Soc Echocardiogr.
2010;23(7):685–713; quiz 86–8.
Transthoracic Doppler Echocardiography
EnyoAblordeppey andAaronMurphy-Crews
7
Learning Objectives
1. Understand the basic principles of Doppler
ultrasound.
2. Be able to optimize the acquisition of Doppler
images and measurements.
3. Become familiar with specic Doppler applications, indications, and clinical relevance.
4. Optimizing spectral and color Doppler by
minimizing aliasing and adjusting the pulse
repetition frequency.
5. Understand Doppler measurements from the
LV inow (mitral valve) and LV outow (aortic valve).
6. Understand Doppler measurements from the
RV inow (tricuspid valve) and RV outow
(pulmonic valve).
7. Understand venous ow patterns from the
pulmonary and hepatic veins.
8. Be able to describe color Doppler for valvular
regurgitation and stenosis.
Doppler is an essential tool for the echocardiographer looking to expand their skill set
beyond basic views and interpretation. Color,
E. Ablordeppey (*)
Emergency Medicine, Washington University School
of Medicine, St. Louis, MO, USA
e-mail:
ablordeppeye@wustl.edu
A. Murphy-Crews
Division of Critical Care Medicine, Department
of Anesthesiology, Washington University School
of Medicine, St. Louis, MO, USA
pulse wave, and continuous wave Doppler allows
for the visualization and measurement of blood
ow through the heart, thereby unlocking the ability to assess valvular abnormalities, noninvasive
measurement of pulmonary arterial pressure, diastolic functioning, stroke volume, and much more.
In this chapter, we will discuss techniques for
optimizing the use of Doppler tools and provide
an overview of individual clinical applications of
Doppler during a focused echocardiography.
Artifacts and pathology associated with Doppler
will be discussed in separate chapters.
General Approach
The convention for a comprehensive TTE is to
apply Doppler modality over each valve in the
same order, starting with color, then pulse wave,
continuous wave, and lastly tissue Doppler. This
approach is efcient for the sonographer as it
obtains all the relevant data at each view for an
economy of scanning. However, bedside clinicians are typically more focused on simultaneously obtaining and interpreting views to answer
focused and immediate clinical questions. Thus,
we have organized the material in this chapter
around specic clinical questions rather than a
comprehensive anatomical approach. An overview of clinical questions and related Doppler
applications can be found in Table
of this chapter, the reader will have a framework
7.1. At the end
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2025
M. J. Lanspa, A. T. Levinson (eds.), Echocardiography and Ultrasonography in the ICU,
Respiratory Medicine,
https://doi.org/10.1007/978-3-031-80038-2_7
73
74
a
b
E. Ablordeppey and A. Murphy-Crews
Table 7.1
Clinical assessment Doppler applications
Cardiac output LVOT VTI (PW Doppler)
Fluid responsiveness Variability in SV via LVOT VTI in response to respiratory cycle or uid bolus/passive
Focused RV assessment TR max for PASP (CW Doppler)
LV diastolic function MV e/a (PW Doppler)
Clinical questions and related doppler applications
leg raise
PAAT (PW Doppler)
RV S′ for RV function (TDI)
Septal and lateral e′ (TDI)
Pulmonary vein (PW Doppler)
for moving toward a more comprehensive skill
set with Doppler applications that can be easily
tailored to focused exams when indicated.
Principles ofDoppler
Echocardiography
The use of Doppler echocardiography relies on
the Doppler effect, which is the principle that
waves will change in frequency when an observer
Fig. 7.1 Doppler shift equation (a), which can be rear-
ranged to calculate blood velocity (b). The Doppler shift
is a change in frequency (∆f) calculated from the speed of
blood (v), the speed of ultrasound waves through the tissue (c), the original US frequency (f
the angle (cosθ) between the direction of blood ow and
the ultrasound probe
), and the cosign of
0
is moving relative to the wave source. You have
experienced the Doppler effect, perhaps without
realizing it. Imagine standing on a street as an
ambulance passes you. As the ambulance
approaches, the siren has a higher pitch (frequency), which changes to a lower pitch as it
heads away. Similarly, ultrasound waves emitted
by the probe change speed when they encounter
blood cells or tissue and are reected at higher or
lower speeds as a result, which can be measured
by the ultrasound machine. The relationship
between frequency and velocity is quantied in
the Doppler shift equation (Fig.
7.1)
There are multiple types of Doppler ultrasound that vary in their function and application
(Fig.7.2).
Color Doppler displays the mean velocities
of blood ow by visual color. Traditionally, blood
Pulse wave Doppler (PWD): The ultrasound
alternates between sending and receiving
pulses, which allows the machine to measure
the velocity of blood at a precise location that
is controlled by moving the gate. This precision of location, known as range specicity,
comes at the cost of limiting the frequencies
that can be measured.
Continuous wave Doppler (CWD): The ultra-
sound is continuously sending and receiving
signals, which removes the limit to measurable frequency but lacks range specicity.
Tissue Doppler imaging (TDI): Similar to
PWD, but with a lter to remove highfrequency signals (typically blood moving
fast) to focus on the slower movement of car-
diac tissues.
moving toward the probe is in the red spectrum,
and blood moving away from the probe is in the
blue spectrum. Faster velocities of ow are
brighter shades of red or blue.
Spectral Doppler plots velocity on the Y-axis
relative to time on the X-axis. Spectral Doppler
includes three subtypes.
Power Doppler averages the amplitude of
ow for more sensitive detection of ow. It does
not measure the direction of ow.
Information obtained with Doppler about the
speed of blood in the heart can reveal a tremendous amount of relevant clinical data in both
Flow towards the transducer
7 Transthoracic Doppler Echocardiography
Frequency
Wave length
Flow away from the transducer
Frequency
Wave length
Fig. 7.2 Frequency and wavelength, inverse relationship relative to the observer
75
static and dynamic assessments. This information is highly dependent, however, on the quality
of our images and measurements. There are functionally two major contributors to image quality:
those relating to the physics of image acquisition
and those relating to machine processing power.
In the next section, we will address strategies to
optimize our Doppler images.
Optimization ofSpectral Doppler
Window Selection andProbe
Positioning
Note that the Doppler shift (see Fig. 7.1) is
dependent on the angle between the moving
object and the receiver. The accuracy of speed
measurements via the Doppler effect will be best
when the movement is directly parallel to the
beam. As the angle becomes more oblique, the
accuracy drops off steeply. For example, at an
angle of 20°, there is only a 6% difference
between the measured and actual speed. At 60°,
the measurement is off by 50%. Thus, window
selection and optimal Doppler interrogation are
essential in Doppler echocardiography to obtain
accurate results. For this reason, many measurements are best obtained through specic windows in order to align the probe as parallel to the
direction of blood ow as possible.
Spectral Broadening
When measuring laminar blood ow with PWD,
the blood cells move with relatively uniform
velocities, thus the spectral envelope should
appear narrow with a clear window underneath.
The loss of this clear window is referred to as
spectral broadening (Fig.
ing can be secondary to user technique as well,
such as with unnecessarily high gain, wide PWD,
or misplacement of the gate along the edge of a
structure where nonlaminar ow is expected.
This is commonly seen when attempting measurements with challenging windows, and the
presence of spectral broadening can be useful
feedback to the sonographer that the acquisition
should be optimized if possible, or if not, that the
measurements may be of limited quality. Of note,
even with optimal technique, spectral broadening
may be seen as an indicator of nonlaminar ow in
cases of valvular stenosis.
7.3). Spectral broaden-