High-Quality Transesophageal Echocardiography

By David T. Linker

High-Quality Transesophageal Echocardiography presents a step-by-step approach aimed to help readers understand how to perform a high-quality transesophageal echocardiogram. The book explains the steps, tips, tricks, and troubleshooting tactics for performing a transesophageal echocardiogram effectively and with highest diagnostic utility, while ensuring patient safety and comfort.

High-Quality Transesophageal Echocardiography is suitable for a wide audience from early learners of the technique who want to accelerate their progress and boost their confidence to those already qualified in the procedure who want to pick up tips to increase the quality and effectiveness of their practice.

• Divides the procedures into easy-to-read sections, allowing readers to quickly refer to a specific section on the go
• Features colored illustrations to help with understanding, as well as animations and videos in the e-book version
• Provides detailed explanations for all parts of the procedure, including tips for imaging specific structures.

• Language: English
• Publisher: Academic Press
• Release date: Jan 27, 2022
• ISBN: 9780128230992

David T. Linker

David Linker is an associate professor of medicine and bioengineering at the University of Washington and the director of the inpatient cardiology consultation service at University of Washington Medical Center in Seattle, Washington, USA. In addition to his 40 years of experience in general cardiology and 30 years of performing transesophageal echocardiography, he is an expert in congenital heart disease and echocardiography. His current research focuses on teaching of procedural skills and new methods for costeffective diagnosis of asymptomatic atrial fibrillation to prevent stroke. He was the engineering project leader for one of the world’s first intravascular ultrasound systems. In addition, Dr. Linker participated in the creation of the Seattle Heart Failure Model, a practical tool to help physicians and patients understand the potential benefits of therapies. He is board-certified in internal medicine, cardiology, and pediatrics and is a fellow of the American College of Cardiology, the American Society of Echocardiography, and the European Society of Cardiology.

Book preview

High-Quality Transesophageal Echocardiography

David T. Linker, M.D., F.A.C.C, F.E.S.C, F.A.S.E

Associate Professor of Medicine in Cardiology, University of Washington, Seattle, Washington, United States

Table of Contents

Cover image

Title page

Copyright

Preface

Acknowledgments

Notes on the figures

Chapter 1. Introduction and how to use this book

How to use this book

Part I. Practical

Chapter 2. Design and physical features of the probe

Overall structure of the probe

The transducer

The movable tip

The body

The control handle

Chapter 3. Patient safety and comfort

Airway and sedation considerations

Patient specific considerations

General considerations

Procedural plan

Consent

Chapter 4. Introduction of the probe

Anesthetizing the oropharynx

Positioning of the patient

Use of a bite block

Other considerations

Inspecting and preparing the probe

Breakdown of steps in inserting the probe

Passing the larynx

Chapter 5. Positioning and moving the probe

Surveying a structure

Moving from one structure to another

Chapter 6. Optimizing image quality

Echo windows

Centering a structure

Unobstructed views

Problems and solutions

Alternative presentations

Optimizing for 3-D

Chapter 7. Strategies for specific structures

Left ventricle

Aortic valve

Aorta

Mitral valve

Left atrium

Left atrial appendage

Pulmonary veins

Atrial septum

Right atrium

Tricuspid valve

Right ventricle

Chapter 8. An effective examination sequence

Chapter 9. End of the examination, and post-procedure

Removal of the probe

Safety of the patient

Documentation and communication

Processing of the probe

Part II. Theoretical

Chapter 10. Ultrasound

Transmission, reflection and generation of ultrasound

Spectral Doppler

Color Doppler

Three-dimensional imaging

Mechanical and thermal index

Chapter 11. Instrumentation

Control panel

Depth and focus

Structural imaging parameters

Frequency and tissue harmonic imaging

Power and temperature

Dynamic range, compression and gray map

Color flow map

Glossary

Chapter 12. Anatomy

Variability of tipping of the left ventricle in the sagittal plane

Presence of echo windows

Variability of orientation of the mitral valve

Variable orientation of the right ventricular outflow tract and main pulmonary artery

Relation of descending aorta to left heart and arch to the descending aorta

Size relationship of the oropharynx to the probe

Anatomy of the esophagus and larynx

Part III. Resources

Chapter 13. Resources

Index

Copyright

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Notices

Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary.

Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility.

To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein.

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ISBN: 978-0-12-822932-3

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Preface

Learning a new skill is challenging. Transesophageal echocardiography is no different, and the complexity is increased because of the need to coordinate what is being done with the knowledge of anatomy, pathophysiology, patient safety, and the mechanics of the procedure itself. The main goal of this book is to give a step-by-step guide for those learning the procedure, emphasizing important details they need to know, choices to make, and recommendations for how to do the procedure.

The information is organized in segments which can be read when needed. The concepts are presented in a sequence designed so that each part builds on previous material. There are over 30 lists that summarize important points from the text for quick reference. It is expected that this approach will speed the development of skill and enhance the confidence of trainees learning transesophageal echocardiography.

This book will also be useful for graduates well-practiced in transesophageal echocardiography who strive for mastery. True mastery is an aspirational goal that is never fully accomplished. The road to mastery involves deliberate practice: investigating every part of the procedure, considering how it can be improved, and learning from others. I hope that even those expert in transesophageal echocardiography will find some new ideas to use.

David T. Linker, M.D., F.A.C.C, F.E.S.C, F.A.S.E

Associate Professor of Medicine in Cardiology, University of Washington, Seattle, Washington, United States

Acknowledgments

Although this is a single-author book, there have been many people who have contributed directly or indirectly to its creation. A complete accounting would be impossible, but I have tried to remember the key influences and support for this process. They are, in a partially chronological order, as follows.

The list starts with my parents, Hal and Halla Linker. They instilled in me values of caring for people, intellectual curiosity and integrity which have served me well. My step-grandfather, Stefán Jóhannsson, taught me the value of attention to detail in performing a mechanical task.

During my time in medical school, I was greatly influenced by three teachers, who each deserve mention. Dr. Stanley Schrier had a way of explaining complex topics with enthusiasm and crystal clarity that I have attempted to emulate during my career. Dr. William Creger connected teaching medical topics with a philosophical appreciation of the thought processes itself, while incorporating references to great literature on the human condition. Dr. Gerald Reaven showed me how a rigorous practice of medicine could be disguised successfully when interacting with a patient in a personable manner.

My education in echocardiography has been dominated by three greats in the field. Dr. Alan Pearlman was my first echocardiographic mentor, giving me an appreciation for detail and analysis which was then continued by my second mentor Dr. Richard Popp. I then had the great fortune to work with Dr. Liv Hatle to benefit from her extraordinarily deep understanding of physiology, including how to apply that knowledge in clinical practice and in the interpretation of echocardiograms.

I was taught transesophageal echocardiography by Dr. René Geuskens. Dr. Lex van Herwerden taught me his surgical analysis of the mitral valve using epicardial echocardiography. His thoughtful, analytical approach influenced my method of examining the mitral valve using a perpendicular sweep oriented toward the long axis as described in this book.

I am grateful to Drs. David Godwin and Martin Gunn here at the University of Washington for their assistance in providing CT scans that I used for some of the illustrations.

Drs. Sophia Larson and Jerry Nnanabu helped me create some of the images for chapter one.

A number of people have read some chapters of this book. I have benefited greatly from their recommendations, and any errors or omissions that remain most likely are because of my not following their excellent advice. My readers were Drs. Alan Pearlman, James Kirkpatrick, Alex Taylor, and Saate Shakil. Dr. Alan Hillel gave helpful comments regarding anesthetizing the oropharynx.

In addition, I am deeply grateful for the indulgence and support of my family, particularly my wife, Margaret, while I spent countless hours at my computer writing this book.

Notes on the figures

It is reasonable for the reader to wonder about the source of the images and whether these were cherry picked over the span of years if not decades. That is not the case. All the transesophageal echocardiogram images in Part I were obtained in a 7-month period by the author during his routine clinical work. The images were mostly collected by postdoctoral fellows in cardiology who were performing the procedure under the supervision of the author. Occasionally, the author would handle the probe to obtain an image illustrating a particular point. The intent of the illustrations is not to show the most beautiful image of a particular structure or feature but demonstrate details important to performing the procedure.

The images were exported as bitmaps and modified in Photoshop (Version 22.4.3, Adobe, Inc.). All the images were cropped, and the resolution was increased or better reproduction. For some of the images, the brightness and contrast were altered, and some extraneous details may have been removed for clarity in illustrating a particular point.

Many of the diagrams incorporate clinical CT scans that have been significantly altered by removing many of the details, inverting grayscale, and posterizing the result. This was all also done in Photoshop. Figs. 4.2–4.5 were all based on a single image that was processed this way, and then warped to result in the changes seen. Illustrations in Figs. 6.1, 6.2, 7.5, 7.8, 9.1, 12.1, and 12.5 were similarly created from cross-sections from an example CT scan from 3D Slicer (https://www.slicer.org/).

Some of the nonechocardiographic color illustrations are based on photos obtained from Morguefile (https://morguefile.com/). These include the mouth and tongue in Fig. 3.1, the car in Fig. 10.8, and the wheel in Fig. 10.10. All these images were also simplified, details were removed, and they were posterized. The images of the larynx in Figs. 2.3, 4.1, 9.1 and 12.7 were modified from an online video of laryngoscopy (https://www.youtube.com/watch?v=hsAkzGdmt8Y), and the soft palate in Fig. 3.1 comes from the same video.

The ultrasound simulations in Figs. 10.2–10.7 were created in MATLAB (version 2020a, The Mathworks, Inc.) using custom software for ultrasound beam simulation written by the author.

All other figures and illustrations were created by the author using Photoshop or illustrator (version 25.4.1, Adobe, Inc.).

Chapter 1: Introduction and how to use this book

Abstract

Performing transesophageal echocardiography is a complex task requiring a knowledge of anatomy, pathology, three-dimensional relationships, ultrasound instrumentation, the operation of the probe, and specific physical skills, at a minimum. Attempting to learn all of these facets simultaneously can be overwhelming. This chapter outlines the approach of this book, which is to break down the procedure sequentially into smaller parts that can be studied individually. This approach is helpful for beginners, but also there is value for experienced practitioners to re-examine each part of the procedure to aim toward mastery. The summary categories that will be used throughout the book are also introduced: Details to Remember, Choices to Make, and Preferences to Consider.

Keywords

Mastery; Practical techniques; Stepwise approach; Transesophageal echocardiography

Transesophageal echocardiography has been in clinical use since the early 1980s and is inarguably a valuable diagnostic tool in cardiology and cardiac anesthesia. Numerous texts cover the clinical use, image interpretation, pitfalls, calculations, standards, and clinical application, among other topics. There is little discussion, however, on the details of the technique itself, other than a few paragraphs on positioning the patient, probe insertion, and obtaining views.

Learning the procedure of transesophageal echocardiography is challenging. It requires a practical knowledge of anatomy of the heart and oropharynx, the pathophysiology being evaluated, the physics of ultrasound, the control of the ultrasound machine, and non-intuitive manipulation of the ultrasound probe itself. All of this is done while performing an invasive procedure, considering the safety and comfort of the patient, and being sure to answer the clinical questions as definitively as possible. Since this is a motor activity, there is also physical skill which must be learned and practiced, much like a sport or musical instrument.

The result of this is that learning the procedure can be stressful, and the student can easily be overwhelmed, or at a minimum have difficulty retaining the all the information provided. A solution to this issue is to break the material to be learned into manageable sections which are small enough so as not to cause overload, and each of which has well-defined concepts. These can be in a progression, so that each part builds on what has gone before, eventually building up quite complex concepts from their component parts.

That is the approach of this book. It is intended as an adjunct to learning the procedure under the guidance of one or more experienced practitioners. Nothing can replace the actual performance of the procedure with the feedback of an expert teacher. This book takes a stepwise approach to understanding the relevant details that will influence safety, comfort, ease, and utility of the procedure. These steps build on each other in a way that will improve the learner's confidence during the process.

At the same time, there is so much to learn, that reading this book will have prepared the student to incorporate additional important details when performing the procedure itself, maximizing the educational benefit of each mentored procedure.

In many ways, learning transesophageal echocardiography is analogous to learning any other complex skill. There is a difference between being able to perform the skill and mastering it. The latter requires an attention to detail, and breaking the skill down into its component parts, optimizing each of those parts, and subsequently reintegrating all of the steps. That is the approach in this book.

Because of this, it can also be of use to those already skilled in the performance of transesophageal echocardiography, in addition to beginners. Although much will be familiar to experienced practitioners, there are bound to be useful details that they can use to augment their practice.

There is no one right way to perform a transesophageal echocardiogram, although there are many wrong ways! This book tries to focus on the aspects of the procedure that are universal, regardless of the variations of technique. That said, there are some aspects for which there are many approaches. There has been no attempt to be exhaustive in enumerating the possible alternatives. Instead, the principles behind choosing an approach are outlined, along with the author's preferred approach, and a few selected variations.

A useful classification of the information to be learned is to organize it into Details, Choices, and Preferences. Details refers to factual information such as the structure of the probe, the physics of ultrasound, anatomy or particular patient that are important to understand if we are to perform the transesophageal echocardiogram optimally. Choices refers to alternative approaches, each of which has advantages and disadvantages, which can be useful in particular situations, or favored by different practitioners. Finally, there are Preferences which are the choices that each expert practitioner makes most frequently.

Details are the same for everyone and keeping them in mind can inform planning and performance of the procedure. The first important point of choices is to realize that they exist, and that there is not just one way to do things. Once we realize this, we expand our scope of alternatives, and we can consider how the specific details impact the choices we make in the context of the current study. Each experienced practitioner will have choices that they favor which we will call Preferences. A great deal of the value of working with an experienced practitioner is learning alternate choices and understanding when to adapt the approach based on the constraints of the particular details.

How to use this book

The book is divided in three parts, each of which has a different function.

Part I - Practical is the stepwise instruction in the procedure itself, and is the core content of the book. It is best to read this in order, since each section builds on the preceding sections. This part of the book stands alone.

It begins with the construction of the probe itself, highlighting details which affect how it is used and behaves when manipulated, as well as how it interacts with the patient. The following chapters are on patient preparation and safety, introduction of the probe, positioning the probe, methods for imaging quality, navigating between structures, and then a large chapter with sections on strategies for particular structures. This is followed by a chapter on how to perform the