Clinical Echocardiography of the Dog and Cat

Eric de Madron, Valérie Chetboul, Claudio Bussadori

• Publisher: Elsevier Masson
• Year: 2015
• ISBN:
  9780323316514
• Topic: Medicine
• Subtopic: Veterinary Medicine

Covering both classical modalities of echocardiography and newer techniques, Clinical Echocardiography of the Dog and Cat shows how to assess, diagnose, and treat canine and feline heart disease. A clinical approach demonstrates how these modalities may be used to acquire images, and then how you can recognize and identify patterns, relate them to different diseases, and manage patient care with those findings. The print book includes a companion website with 50 videos of cardiac ultrasound exams and procedures. Written by veterinary cardiology specialists and echocardiographers Eric de Madron, Valerie Chetboul, and Claudio Bussadori, this indispensable echocardiology resource is ideal for general practitioner veterinarians as well as specialists, including cardiologists and radiologists.

• Dedicated coverage of canine and feline echocardiography emphasizes a more in-depth discussion of cardiac ultrasound, including the newest ones such as Tissue Doppler and speckle tracking imaging, and transesophageal and 3D echocardiography.
• A practical, clinical approach shows how these echocardiographic modalities are not just research tools, but useful in diagnosing and staging heart disease in day-to-day practice.
• Book plus website consolidates offers current information into a single cohesive source covering classical modalities and newer techniques, as well as updates relating to normal echocardiographic examinations and values.
• 50 videos on the companion website demonstrate how to perform echocardiography procedures, illustrating points such as swirling volutes, color flow display of blood flows, dynamic collapses secondary to pericardial effusion, and tumors flicking in and out of the echocardiographic field.
• A section on presurgical assessment helps you assess risk and prepare for catheter-based correction of cardiac defects — accurate measurements and proper device selection are key to a successful procedure.
• Over 400 full-color illustrations and 42 summary tables help you achieve precise, high-quality imaging for accurate assessment, including photographs of cadaver animal specimens to clarify the relationship between actual tissues in health and disease and their images.

Part I

Normal Echocardiographic Examination

Outline

1. Normal Views: 2D, TM, Spectral, and Color Doppler

2. Normal Echocardiographic Values: TM, 2D, and Doppler Spectral Modes

3. Intra- and Interoperator Variability

1

Normal Views

2D, TM, Spectral, and Color Doppler

Éric de Madron

The Different Modes, 4

General Considerations, 5

Normal Bidimensional Views, 6

Normal TM Views, 16

Normal Spectral Doppler Examination, 17

Color Doppler, 18

The Different Modes

Bidimensional Mode

Bidimensional (2D) echocardiography provides anatomic cross-sections of the heart via the emission of a wide ultrasound beam through the thorax and the reception of the echoes reflected by its different structures. This wide beam allows viewing of a large part of the organ. It is shaped in such a manner as to travel between the ribs and the pulmonary lobes. Several views or projections are used in order to observe all of the cardiac structures. 2D echocardiography allows real-time visualization of the movement and deformation of these structures in two dimensions. Bidimensional harmonic echocardiography integrates secondary harmonics of reflected echoes. This improves the visualization of structures with low levels of reflectivity, such as the myocardium.

Time-Motion Mode

Historically, time-motion (TM) mode (or M-mode) was the first mode developed. A line is selected on the 2D ultrasound cone and a series of points moving in time can then be obtained. These points correspond to the echoes reflected by the different acoustic interfaces of each cardiac structure being penetrated. The point of origin and orientation of this line can be modified if the device is equipped with “anatomic” or “free-angle” M-mode capabilities. Because of the contraction and dilation of the heart, the position of these points will vary according to the cardiac cycle phases. This appears on the screen as undulating lines corresponding to the movement of the points over time. Due to high sampling frequency, TM mode enables the recording of very rapid cardiac movements such as valve motion [1,2]. It also allows measurement of the dimensions of the heart (wall thickness and endocavitary diameters in systole and diastole) and analysis of the motion of different structures of the organ during the cardiac cycle.

Spectral Doppler Mode

When an ultrasound beam of a particular frequency encounters a flow of erythrocytes moving at speed S, part of these ultrasounds is reflected toward the transducer at a modified frequency. This is defined as the Doppler effect [3,4]. This change in frequency, or shift, is proportional to the speed of the erythrocytes (i.e., the blood flow speed) and to the angle cosine (referred to as θ) formed by the ultrasound beam and the blood flow axis of displacement according to the equation:

V=(ΔF×C)/(2F0×cosθ)

where ΔF is the measured frequency shift, C is the initial ultrasound speed in the soft tissue, and F₀ is the initial beam frequency [3]. The Doppler examination, by measuring this ΔF frequency shift, allows the determination of the blood flow velocity and its direction. To best measure real flow velocity without underestimating it, the θ angle must be as close to 0 degrees as possible. The ultrasound beam must then be aligned as much as possible to the axis of the flow movement.

The Doppler examination allows the study of the characteristics of the intracardiac flows, the detection of abnormal flows, and the measurement of transvalvular or transorifice stroke volumes.

The spectral Doppler exam includes pulsed and continuous wave Doppler modes, which complement each other perfectly. In both cases, the frequency shift is analyzed and filtered by the cardiac ultrasound machine, which transforms it into acoustic and graphic signals. The graphic signal represents the spectral analysis through fast Fourier transform of all reported frequency shifts in the flow under study. A velocity “envelope” changing in time can thus be obtained. As a rule, when erythrocytes move toward the transducer, their velocities are coded as positive. Inversely, they are coded as negative when moving away from the transducer. Not all red cells within a blood flow move at the same velocity. The Doppler signal will indicate through its intensity the relative prevalence of these velocities. In a normal transval...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• The Authors
• Abbreviations
• Preface
• Video Credits
• Part I. Normal Echocardiographic Examination
• Part II. New Cardiac Ultrasound Imaging Techniques
• Part III. Hemodynamic Evaluation
• Part IV. Echocardiography of Acquired Cardiopathies
• Part V. Congenital Cardiopathies
• Index