ECGs for Beginners

Antoni Bayés de Luna

• Publisher: Wiley-Blackwell
• Year: 2014
• Print ISBN: 9781118821312
• eBook ISBN: 9781118821329
• Edition: 1
• Topic: Medicine
• Subtopic: Physiology

Mastery of ECG interpretation is achievednot only by pattern recognition, but equally importantly, by aclear, practical understanding of how electricity moves through the heart and how disruption of that movement manifests itself viaECG tracings. ECGs for Beginners, written byone of the world's most respected electrophysiologists with over 40 years experience of training clinicians, will provide cardiology and electrophysiology trainees with an easy to follow, step-by-stepguide tothe topic, thus enabling them to both understand and interpret ECG readings in order to to best manage their patients. Packed with over 250 high-quality ECG tracings, as well as management algorithms andkey points throughout, every chapter also contains self-assessment questions, allowing the reader to test themselves on what they've just learnt. All kinds of arrhythmias will be covered, as well as morphologicalabnormalities such asatrial and ventricular problems. Importantly, normal ECG readings will be presented alongside abnormal readings, to best demonstratehow and why abnormalities occur. ECGs for Beginners is anessential purchase for all cardiology and electrophysiology trainees, as well as beinga handy refresher guide for the experiencedphysician.

PART I
The Normal Electrocardiogram

In the first chapter the anatomical and electrophysiological bases essential to understanding the human electrocardiogram (ECG), are outlined. Chapter 2 explains how the ECG records the path of cardiac activation through the heart from the sinus node to the ventricular muscle in the form of activation curves (depolarization and repolarization) of the atria (P waves) and ventricles (the QRS-T complex). Chapter 3 describes ECG devices and recording techniques. Lastly, Chapter 4 explains in detail the process for interpreting normal and pathologic ECG recordings, including the normal characteristics of each parameter studied.

A full understanding of these concepts is essential before continuing on to the other parts of the book. Please start the first four chapters again if necessary.

CHAPTER 1
Anatomical and Electrophysiological Bases

1.1. The Heart Walls

The heart has four cavities, two atria and two ventricles, comprised mainly of contractile cells called cardiomyocytes. The electrical stimulus originating in the sinus node (SN) is distributed through the entire heart by means of a specific conduction system (SCS).

The left ventricle (LV) has four walls: anterior, septal, inferior, and lateral. Figure 1.1 shows the three segments of the anterior and inferior walls, the five segments of the septal and lateral walls, and the apex segment (segment 17). Magnetic resonance imaging has now shown that the previously-named posterior wall corresponds to the inferobasal segment of the inferior wall (segment 4 in Fig. 1.1) (Bayés de Luna et al., 2006a; Bayés de Luna A and Fiol-Sala, 2008). [A]

Figure 1.1 (A) Segments into which the left ventricle is divided according to the transverse (short-axis) sections performed at the basal (B), medial (M), and apical (A) levels. The basal and medial sections delineate into six segments each, while the apical section shows four segments. Together with the apex, they constitute the 17 segments into which the left ventricle can be divided, according to the classification performed by the American Imaging Societies (Cerqueira et al., 2002). Also shown is the view of the 17 segments with the heart open in a horizontal long-axis plane (B) and vertical long-axis (sagittal-like) plane (C). In D, the 17 segments and the four walls of the heart are shown in a ‘bull's-eye view’. RV = right ventricle.

1.2. Coronary Circulation (Fig. 1.2)

Based on coronary perfusion, the heart is divided into two zones: the anteroseptal zone, perfused by the left anterior descending artery (LAD) (Fig. 1.2A) and the inferolateral zone, perfused by the right coronary artery (RCA) and circumflex artery (CX) (Figs 1.2C and 1.2D). The heart has areas of shared perfusion (shown in grey in Fig. 1.2A) in which one of the two arteries dominates. For example, segment 17 (apex) is perfused by the LAD, if long; otherwise by the RCA and even partially by the CX. [B]

Figure 1.2 According to the anatomical variants of coronary circulation, the areas of shared variable perfusion are shown in grey (A). The perfusion of these segments by the corresponding coronary arteries (B–D) can be seen in the ‘bull's-eye’ images. For example, the apex (segment 17) is usually perfused by the LAD but sometimes by the RCA, or even the LCX. Segments 3 and 9 are shared by LAD and RCA, and also the small part of the mid-low lateral wall is shared by LAD and LCX. Segments 4, 10 and 15 correspond to the RCA or the LCX, depending on which of them is dominant (the RCA in >80% of the cases). Segment 15 often receives blood from LAD.

1.3. The Specific Conduction System (Fig. 1.3)

Electrical stimuli pass through the internodal pathways (Bachmann, Wenckebach and Thorel bundles), from the sinus node to the AV node and the His bundle. From there stimuli reach the ventricles through the ventricular conduction system: the right branch (RB) and the trunk of the left branch (LB), and its divisions (superoanterior and inferoposterior fascicles and the middle fibers that exist between them) (Figs 1.3A and 1.3B). [C]

Figure 1.3 (A) Right lateral view of the specific conduction system. 1, 2 and 3: internodal tracts; 4: AV node; 5: bundle of His; 6: left branch; 7: right branch with its ramifications; Ao: aorta; AVN: AV node; CS: coronary sinus; FO: fossa ovalis; IVC: inferior cava vein; SN: sinus node; SVC: super...

Table of contents

• Cover
• Table of Contents
• Title page
• Copyright page
• Preface
• Forewords to Previous Editions
• Foreword
• PART I: The Normal Electrocardiogram
• PART II: Morphological Abnormalities in the ECG
• PART III: The ECG in Arrhythmias
• PART IV: ECG in Clinical Practice
• Bibliography
• Supplemental Images
• Index
• End User License Agreement