Ebook A practical approach to clinical echocardiography Part 1

A Practical Approach to
Clinical Echocardiography



A Practical Approach to
Clinical Echocardiography

Jagdish C Mohan MD DM FASE
Director of Cardiac Sciences
Fortis Hospital
Shalimar Bagh, New Delhi, India

Foreword
Bijoy K Khandheria

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A Practical Approach to Clinical Echocardiography

First Edition: 2014
ISBN 978-93-5152-140-2
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Dedicated to
Vineet, my soul-mate for the last thirty-six years



Foreword
The field of cardiovascular ultrasound continues to explode with an increase in applications and rapid
explosion in technological advances. It was not too long that the world celebrated the 50th anniversary of
cardiac ultrasound. The remarkable progress continues, and the evolution to revolution has yet to see a stop.
With ever-increasing applications and explosion of technology comes the need to transmit this
information in an easy-to-understand, easy-to-digest manner. To this end, Prof Jagdish C Mohan has
exploited the method of making difficult things easy in this book. The book is eminently readable. Strength, weakness
and caveats of every important echo-Doppler observation have been provided. The images and the illustrations are
excellent with extensive labeling for easy understanding. There is less emphasis on bibliography and more on practical
tips. Although there are no separate chapters on transesophageal echocardiography and real-time 3D imaging, these
have been well covered in individual sections wherever appropriate. The same principle has been applied to contrast
echocardiography.
There is little doubt that cardiovascular ultrasound will continue its revolution, and play an important role in the
practice of cardiology as well as medicine. This book compiled by Prof Jagdish C Mohan is a welcome addition to the
various sources of education in this field. It is a must-read book for those wishing to practice the art and science of
cardiovascular ultrasound.
Bijoy K Khandheria MD FACP FAHA FACC FESC FASE
Adjunct Clinical Professor of Medicine
University of Wisconsin, School of Medicine and Public Health
Director, Echocardiography Services

Aurora St Luke’s Medical Center, Milwaukee, Wisconsin, USA
Director, Echocardiography Center for Research and Innovation
Aurora Research Institute, Milwaukee, Wisconsin, USA
Past President, American Society of Echocardiography
Former Chair of Cardiovascular Disease, Mayo Clinic, Arizona
Former Professor of Medicine, Mayo Medical School



Preface
Echocardiography is the most commonly used imaging technique at bedside, in OR, in outpatients and in community
screening. It is highly portable, noninvasive, repeatable, inexpensive and easily accessible. When used appropriately
after some experience, it has inherent internal validation unlike many other imaging modalities. Clinicians using this
technique transcend boundaries of specialties. More and more physicians want to learn and practice it. Despite these
obvious advantages, this modality remains incompletely utilized. There are several learning modules in capsule form
and a multitude of books which claim to make a person expert in short time. In these, either there is over-simplification
or meaningless convoluted and complicated equations and biophysical complexity. At fringes, are clinicians who have
used this technique year after year for assessment of left ventricular function only. Echocardiography represents a
strange mixture of several features which have proven prime-time use and an equally numerous techniques which have
yet to show clinical utility despite extensive research work spanning decades. There is an urgent need to promote that
part of science which has robust validation. What clinicians require needs to be emphasized with clarity. Novices often
get unnerved by the available applications on the systems which are more to stand up to the competition rather than
of tangible clinical value. However, extensive research has shown applicability of a lot of echocardiographic knowledge
and information in day-to-day evidence-based medicine. Quantitative and semi-quantitative protocols are gaining
ground because these make serial follow-up easily. This book is an attempt to make echocardiography simple, practical
and easily usable with reproducible data. Unnecessary and impractical details have been omitted. I would welcome
suggestions to make it more readable and meaningful.
Jagdish C Mohan

Acknowledgments
I appreciate the contribution of M/s Jaypee Brothers Medical Publishers (P) Ltd., New Delhi, India, in making this
project a success. In particular, Ms Chetna Malhotra Vohra (Senior Manager–Business Development) for her belief in
our groups’ ability to deliver and Saima Rashid (Development Editor) who did very well in making sure we catch-up with
the deadline.



Contents
Section 1: Fundamentals of Echocardiography
1.Echocardiography: Basic Principles, Technique, Display and Interpretation

3

• Ultrasound Physics  3
• Ultrasound Beam  7


2. Hemodynamic Evaluation by Echo-Doppler Techniques
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24

Hemodynamic Evaluation  24
Doppler Principle for Estimating Velocity  25
Ohm’s Law of Fluids (The Hagen–Poiseuille Equation)  27
The Bernoulli’s Equation  28
Continuity Equation  28
Effective Orifice Area  30
Vena Contracta  31
Pressure Recovery  33
Ventriculovalvular Impedance  34
Proximal Isovelocity Surface Area and Volumetric Measurements  34
Pressure Half-Time  36
Lv Dp/Dt 39
Estimation of Pulmonary Artery Pressures and Pulmonary Vascular Resistance  39
Section 2: Valvular Heart Disease



3. Mitral Stenosis

45

• Anatomy of the Mitral Valve  45

4. Mitral Regurgitation

64

• Functional Morphology of Mr 64


5. Aortic Valve Stenosis
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Anatomy of Trileaflet Aortic Valve  83
Unicuspid Aortic Valve  85
Bicuspid Aortic Valve  85
Quadricuspid Aortic Valve  86
Anatomy of Aortic Stenosis  86

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A Practical Approach to Clinical Echocardiography

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6. Aortic Valve Regurgitation
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110

Functional Morphology of the Tricuspid Valve  110
Conditions Affecting Tricuspid Valve  113
Remodelling in Tricuspid Regurgitation  114
Functional Tr 114
Organic Tricuspid Valve Disorders  115
Tricuspid Valve Stenosis  120

Assessment of Severity of Tr 121
Vena Contracta  121
Proximal Isovelocity Surface Area Method  122
Anterograde Velocity of Tricuspid Inflow  122
Hepatic Vein Flow in Assessment of Tr 123

8. Pulmonary Valve
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98

Hemodynamics of Aortic Regurgitation  98
Functional Anatomy of Aortic Regurgitation  100
Detection of Aortic Regurgitation by Echo-Doppler Techniques  102
Volumetric Severity of Aortic Regurgitation  104
Color Flow Doppler Evaluation of Aortic Regurgitation  104
Aortic Regurgitation Assessment by Vena Contracta  105
Proximal Isovelocity Surface Area Flow Convergence Method  105
Diastolic Flow Reversal in the Descending Aorta and Severity of Aortic Regurgitation  106
Pressure Half-time of Aortic Regurgitation Signal  107
M-mode Color Flow Propagation Velocity  108
Summary of Aortic Regurgitation Assessment by Echo-Doppler Methods  108

7.Tricuspid Valve
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Planimetry of the Aortic Valve Area on Aortic Stenosis  87
Hemodynamics of Aortic Valve Stenosis  88
Technical Tips  90
Low-gradient, Low-flow Aortic Valve Stenosis  93
Paradoxical Low-flow as with Preserved Ejection Fraction  95
Subaortic Stenosis  95

126

Anatomy of the Pulmonary Valve  126
Pulmonary Valve Disorders  127
Transesophageal Echocardiography in Pulmonary Stenosis  133
Consequences and Associations of Pulmonary Stenosis  134
Assessment of Pulmonary Regurgitation  134
Consequences of Pulmonary Regurgitation  136

9. Evaluation of Prosthetic Heart Valves

• Ball-in-cage Valve  138
• Tilting or Mono-disk Valve  139

138


Contents

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Bileaflet Prosthetic Valves  140
Bioprosthesis 141
Hemodynamic Assessment of Prosthetic Valves  141
Technical Considerations  148
Microbubble Formation (Cavitation)  152
Prosthetic Valve Dysfunction  152
Bioprosthetic Degeneration  152
Prosthetic and Paraprosthetic Regurgitation  153
Paraprosthetic Regurgitation  154
Prosthetic Valve Stenosis  155

Tricuspid and Pulmonary Prosthetic Valves  160
Section 3: Systolic and Diastolic Function

10. Left Ventricular Systolic Function

165

• Morphology of the Left Ventricle  165
• Limitations 186
11. Echocardiographic Assessment of Right Ventricular Function:
Methods and Clinical Applications
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•
•

Peculiarities of the Right Ventricle  189
Function Parameters  190
Right Ventricle Diastolic Function and Pressures  193
Tricuspid Annular Peak Systolic Velocity  198
Right Ventricle Strain and Strain Rate Analysis  200

12. Diastolic Function
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189

Physiology of Diastole  204
Factors Contributing to Diastole  205
Significance of Diastolic Function  205
Isovolumic Relaxation Time  206
Rapid Filling Phase  207
Deceleration Time of Early Filling Wave (Mitral E- and Pulmonary D-Waves)  207
Diastasis 208
Atrial Kick or Contribution  209
Tissue Motion and Diastolic Function  209
Left Atrial Volume and Diastolic Function/Dysfunction  210
How to Perform a Study Focusing on Diastolic Function  211
Mitral Inflow Velocities  212
Mitral Annular Velocities  214
How to Obtain Annular Tissue Velocities  216
Pulmonary Vein Flow and Diastolic Function  218

Mitral Flow Propagation by Color M-Mode  221
Longitudinal Strain, Rotation and Untwisting Rate by Acoustic Speckle Tracking  223
Diastolic Stress Test 224

204

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A Practical Approach to Clinical Echocardiography

Section 4: Muscle Mechanics
13.Tissue Doppler Echocardiography: Current Status and Applications
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Concept of Tdi 229
Labeling of Tissue Velocity Waveforms  229
Terms Used in Tissue Doppler Imaging  231

Technical Details of Tdi 231
Myocardial Velocities in Short Axis  234
Internal Dependency of Velocities  235
Fundamental Basis of Tdi 236
Tissue Doppler Data Processing for Deformation Imaging  238
Clinical Utility of Tdi 239
Prognostic Value of Tdi in Diverse Cardiac Disorders  250
Limitations of Tdi 251

14. Deformation Imaging: Theory and Practice
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257

Myocardial Deformation  257
Descriptive Terms  261

Acoustic Speckle Tracking  262
Velocity Vector Imaging  264
How to Perform Two-Dimensional Strain Imaging?  266
Effects of Ischemia on Regional Deformation Metrics  268
Early Systolic Longitudinal Lengthening (Paradoxical Longitudinal Systolic Strain)  269
Post-systolic Longitudinal Shortening  270
Paradoxical Strain Patterns  272
Right Ventricular Deformation  273
Left Atrial Function by Deformation Imaging  273
Mechanical Properties of the Aorta  274
Three-dimensional/Four-dimensional Deformation Imaging  274
Clinical Applications of Strain and Strain Rate Imaging  276
Limitations 277

15. Rotation, Twist and Torsion
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229

Fundamentals of Torsion  280
Echocardiographic Methods of Studying Twist  284

Clinical Applications of Torsion  285
Aging and Torsion  286
Aortic Stenosis, Hypertension and Hypertrophic Cardiomyopathy  286
Heart Failure  287
Constrictive Pericarditis  287
Torsion and Cardiac Resynchronization Therapy  288
Acute and Chronic Ischemia  289
Grades of Diastolic Dysfunction and Twist  290

280


Contents

Section 5: CHD, Aorta and Pericardium
16.Congenital Heart Disease in Adults
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Atrial Septal Defect  295
Patent Foramen Ovale  299
Ostium Primum Atrial Septal Defect  299
Sinus Venosus Atrial Septal Defect  300
Common or Single Atrium  300
Ventricular Septal Defect  300
Morphology of Vsd 302
Pathophysiology of Vsd 302
Ebstein’s Anomaly  304
Carpentier Classification of Ebstein’s Anomaly  306
Double-Chambered Rv 307
Sinus of Valsalva Aneurysms  308
Tetralogy of Fallot  311
Morphological Variants of Tof 312
Truncus Arteriosus or Common Arterial Trunk  313
Subaortic Membranous Stenosis  314
Physiology and Pathology  314
Transposition of Great Vessels  315

17. Aorta: Congenital and Acquired Disorders
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318

Structure of Aorta  318
Parts of Aorta  318
Functions of Aorta  320
Normal Aortic Measurements and Imaging Views  321
Etiopathogenesis of Aortic Disorders  322
Congenital Disorders of Aorta  322
Aortic Coarctation  324
Aneurysm of Sinus of Valsalva  325
Aortopulmonary Window  329
Truncus Arteriosus  329
Supravalvular Aortic Stenosis  330
Patent Ductus Arteriosus  330
Acquired Aortopathies  331

18. Pericardial Diseases
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295

Echocardiographic Anatomy of Pericardium  343
Pericardial Disorders  344
Acute Pericarditis and Pericardial Effusion  345
Cardiac Tamponade  349
Pericardial Cysts and Masses  353
Pericardial Constriction 353

343

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A Practical Approach to Clinical Echocardiography

Section 6: Structural Heart Disease
19. Ischemic Heart Disease
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Myocardial Segment Nomenclature and Coronary Vascular Territory  363
Right Ventricular Segmentation  363
Ischemia and Echocardiographic Imaging  365
Echocardiography in Ihd 369
Evaluation of Myocardial Infarction  369
Mechanical Complications of Myocardial Infarction  370
Stress Echocardiography  377

20.Tumors, Masses and Infection
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363

383

Cardiac Manifestations of Masses  383
Cardiac Thrombi and Spontaneous Echo Contrast  384
Cardiac Tumors  385
Echocardiographic Features of Myxoma  387
Papillary Fibroelastoma  388
Malignant Tumors  388

Differential Diagnosis of Cardiac Tumors  389
Infective Endocarditis  389
Points to Remember  392

21.Cardiomyopathies

395

• European Classification of Cardiomyopathies  397
• Summary of Emf Echocardiographic Features  406
Index415


SEction

1

Fundamentals of Echocardiography
Chapters
ÖÖ Echocardiography: Basic Principles, Technique,
Display and Interpretation

ÖÖ Hemodynamic Evaluation by Echo-Doppler Techniques



Chapter

1

Echocardiography: Basic
Principles, Technique,
Display and Interpretation

ˆˆ Introduction
Echocardiography is a technique of generating images of
the heart with the help of ultrasound (like skiagraphy is
performed with X-rays). Echocardiography has become
an integral part of clinical examination with its bedside
mobility and utility. Practice of echocardiography
mandates the following steps:
• Understanding of ultrasound physics
• Knowledge of the instrumentation
• Acquisition skills
• Interpretative skills
• Sound knowledge of cardiovascular anatomy and
physiologies
• Adequate knowledge of common cardiac pathology
• Reporting, storage and retrieval skills.
Ultrasound behaves very differently when it passes
through any tissue. Many of the objects and artifacts seen
in ultrasound images are due to the physical properties
of ultrasonic beams, such as reflection, refraction,
diffraction and attenuation. Indeed, physical artifacts
are an important element in clinical diagnosis (Fig. 1.1).
Appreciating the phenomena created by ultrasound may
greatly benefit the patient in terms of increased accuracy
of interpretation and diagnosis. The ultrasound wave
created for sending through the tissues is called incident
wave. This is the wave whose behavior is changed by the

tissue.

Fig. 1.1: Behavior of the sound waves. Sound wave after striking a
surface gets reflected as well as transmitted into the other medium in a
different direction (refracted). Total internal reflection without transmission occurs if it strikes the interface at 90°.

ˆˆ ULTRASOUND PHYSICS
Sound
Sound is a form of mechanical energy that consists of waves
of compression and decompression of the transmitting
medium, travelling at a fixed velocity (Figs 1.2 and 1.3).
Sound is an example of longitudinal waves oscillating
back and forth in the direction the sound travels,
thus consisting of successive zones of compression


4

Section 1: Fundamentals of Echocardiography

Fig. 1.2: Alternating compression and rarefaction of a medium as
sound passes through it.

Fig. 1.3: Sound as an oscillating wave of mechanical energy.
Compression is accompanied by high pressure and rarefaction by low
pressure.

Why Use Ultrasound in Medicine?

Fig. 1.4: The concept of pulsed ultrasound. If an interface is closure

to the source of ultrasound, more pulses will be received per second
resulting in better resolution.

(high pressure) and rarefaction (low pressure). The
medium particles, however, show both longitudinal and
transverse oscillations.
Longitudinal oscillations: The oscillating particles
of the medium are displaced parallel to the direction of
motion (direction of energy transfer).
Transverse oscillations: The oscillating particles of the
medium are displaced in a direction perpendicular to the
motion of the wave.
Ultrasound: Sound waves with a frequency of 20000
c/s (20 KHz) are labeled ultrasound. Ultrasound used in
medical diagnosis has a frequency of 1–10 MHz.1–3 These
are beyond the capacity of human ear to perceive.

With higher frequencies (shorter wavelengths), the sound
tends to move more in straight lines like electromagnetic
beams and is reflected like light beams. It is reflected by
much smaller objects (because of shorter wavelengths)
and hence gives good spatial resolution. If the wavelength
of the sound is smaller than the object, no noticeable
diffraction occurs.

wavelength = speed/frequency
Frequency: The frequency of an ultrasound wave
consists of the number of cycles or pressure changes that
occur in one second (Fig. 1.2). The units are cycles per
second or hertz (Hz). Frequency is determined by the

sound source only and not by the medium in which the
sound is travelling.
Propagation speed: Propagation speed is the rate
at which sound can travel through a medium and is
typically considered 1,540 m/s for soft tissue. The speed
is determined solely by the medium characteristics like
density and stiffness. Speed is inversely proportional to
density and incompressibility.
Pulsed ultrasound: Pulsed ultrasound describes a
means of emitting ultrasound waves from a source. To
achieve the depth of resolution required for clinical
uses, pulsed beams are used. Typically, the pulses are a
millisecond or so long and several thousands are emitted
per second (Fig. 1. 4).
Ultrasound interaction with tissue: As a beam of
ultrasound travels through a material, various things
happen to it. A reflection of the beam is called an echo,


Echocardiography: Basic Principles, Technique, Display and Interpretation

Fig. 1.5: The concept of an echo.

A

Fig. 1.6: Soft tissue acoustic interface producing some reflection
and more transmission. If a medium has high acoustic impedance,
stronger reflection will occur.

B

Figs 1.7A and B: (A) Tissue interfaces with variable acoustic impedance. Higher impedance produces brighter echo due to more reflection
of ultrasound; (B) Refraction: Bending of the sound wave as it enters another medium. Refraction is associated with decreasing speed and
wavelength.

a critical concept in all diagnostic imaging (Fig. 1.5). The
production and detection of echoes form the basis of the
technique that is used in all diagnostic instruments. A
reflection occurs at the boundary between two materials
provided that acoustic impedance of the materials is
different. This acoustic impedance is a product of the
density and propagation speed.
If two materials have the same acoustic impedance,
their boundary will not produce an echo. If the difference in
acoustic impedance is small, a weak echo will be produced
and most of the ultrasound will carry on through the
second medium. If the difference in acoustic impedance
is large, however, a strong echo will be produced. If the

difference in acoustic impedance is very large, all the
ultrasound will be totally reflected. Typically in soft tissues,
the amplitude of an echo produced at a boundary is only a
small percentage of the incident amplitudes (Fig. 1.6).
Strong reflections or echoes show on the ultrasound
image as white and weaker reflections as gray (Figs 1.7A
and B).
A sound wave will undergo certain behaviors when it
encounters a tissue interface. Possible behaviors include:
• Reflection off the tissue interface
• Diffraction around the interface

• Transmission (accompanied by refraction) into the
interface or new medium (Fig. 1.8)

5


6

Section 1: Fundamentals of Echocardiography

Fig. 1.8: Decreasing wavelength after refraction in the second medium.

Fig. 1.9: Multiple linear shadows (arrows) in front of mitral prosthesis in
transesophageal echocardiographic (TEE) view due to rever­berations.

Fig. 1.10: Reverberations shown by the curved arrow resulting in a
mirror-image artifact.

Fig. 1.11: Reflection from a tissue interface at right angle. There is
stronger reflection resulting in brighter echo. Typically, from posterior
pericardium.

Fig. 1.12: Reflection at an angle equal to the angle of incidence
producing less bright echo.

Reflection of sound waves off of surfaces can lead to
one of two phenomena—an echo or a reverberation.
The reception of multiple reflections off of the interface
causes reverberations—the prolonging of a sound
(Figs 1.9 and 1.10).

Angle of incidence: If a beam of ultrasound strikes the
boundary at right angle, it will be reflected parallel to
the transmitting beam and shall produce stronger echo
(Fig. 1.11). If it strikes a boundary obliquely, the
interactions are more complex than for normal incidence
(Fig. 1.12). The echo will return from the boundary at an
angle equal to the angle of incidence. The transmitted
beam will be deviated from a straight line by an amount
that depends on the difference in the velocity of ultrasound
at either side of the boundary. This process is known as
refraction (Figs 1.1 and 1.7).


Echocardiography: Basic Principles, Technique, Display and Interpretation

Fig. 1.13: Reflection from a large interface is called specular
reflection and appears bright while smaller objects (smaller than the
wavelength) produce acoustic scattering.

Reflection is of two types (Fig. 1.13):
1. Specular reflection: is from a large tissue interface
(smooth boundary between media) and produces
bright echoes. These signals are intense and angle
dependent:
2. Acoustic scattering: occurs from smaller objects.
Scattering is responsible for tissue texture. The signals
are less intense and less angle dependent. These
provide tissue signature to the image.

Attenuation

As sound waves travel through a medium (e.g. tissue or
blood), the intensity weakens or attenuates. The degree
of attenuation is expressed in decibels (dB). Absorption
represents a conversion of sound energy to another
form of energy and is the major reason for attenuation.
Attenuation is greater for high-frequency sounds, which
result in higher absorption and more scatter. Attenuation
coefficient is smallest for the fat and maximum for lungs.
Bones also have very high attenuation coefficient.

Penetration
Depth to which an ultrasound beam travels into a tissue
is called penetration. Besides the tissue characteristic,
penetration is largely dependent upon the frequency of
the ultrasound being applied:

Fig. 1.14: Schematic diagram of an ultrasound beam.

Frequency %

Penetration %

1 MHz

40 cm

2 MHz

20 cm

3 MHz

13 cm

5 MHz

8 cm

10 MHz

4 cm

20 MHz

2 cm

ˆˆ ULTRASOUND BEAM
The sound beam is the confined, directional beam of
ultrasound travelling as a longitudinal wave from the
transducer face into the propagation medium. Ultrasound
beams are made of scan lines. These have length (azimuth)
along their long axis and width (elevation) along their
short axis. Beam width should be as narrow as possible to
prevent beam width artifacts and which can be achieved
by using lens. Ultrasound beams are either steered
mechanically or electrically. Both rapidly sweep sound
waves through tissues (Fig. 1.14).

Imaging Using Ultrasound
Image formation requires an ultrasound machine with

appropriate transducers and display, using a cathode-ray
tube or a flat panel.

7