Learning electrocardiography: a complete course

625 Pages·15.389 MB·English

by  Jules Constant

learning
Electrocardiography
A Complete Course
Fourth Edition

learning
Electrocardiography
A Complete Course
Fourth Edition
Jules Constant mo
State University of New York at Buffalo
Buffalo, NY
informa
healthcare
New York London
CRC Press
Taylor & Francis Group
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Boca Raton, FL 33487-2742
© 2002 by Taylor & Francis Group, LLC
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Version Date: 20130415
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Contents
Preface ix
1. Cardiac Anatomy and Physiology 1
A Brief Note for Beginning Students
2. Electrical Activity of the Heart 5
3. How an Electrocardiograph Works 7
Functions of an Electrocardiograph. How the ECG Machine Measures Current Direction
4. Electrocardiographic Configuration and Nomenclature 11
ECG of Ventricular Depolarization. ECG of Ventricular Repolarization
5. Electrocardiographic Language of Direction 17
6. Bipolar Limb Leads 19
Leads 1, 2, and 3. Triaxial System and Einthoven’s Triangle
7. How to Draw a QRS Vector with the Triaxial System 25
QRS Duration. QRS Direction Recognition. Telling Direction by the Method of Perpendiculars
8. Unipolar Limb Leads 33
9. Frontal Plane Hexaxial System 39
How to Draw a Frontal Plane Hexaxial System. How to Plot Vectors in the Hexaxial System. Semicircle
Method of Plotting Frontal Vectors
LO. Normal Frontal Plane QRS, T, and P Vector Ranges and Patterns 49
Normal QRS Range. Normal T Range. Normal P Range. Indeterminate Axes. Effect of Age and Chest
Shape on QRS Axes
LI. Horizontal Plane Electrocardiogram 59
Placing the Chest Electrodes. How to Plot Vectors in the Horizontal Plane: Horizontal Plane
Hexaxial System. How to Draw a Spatial Vector. Steps in Drawing a Spatial QRS Vector. Horizontal
Plane Normal Vectors. Normal QRS Ranges and Patterns. Electrical Positions of the Heart. Normal T
Ranges and Patterns (Horizontal Plane). Normal P Ranges and Patterns (Horizontal Plane). Pediatric,
Frontal, and Horizontal P, QRS, and T Directions
L2. Normal P, P-R, QRS, and T Height, Width, and Duration 83
L3. Dipole Concept 85
vi Learning Electrocardiography
14. How to Produce a Good ECG Tracing 87
Termiology. Electrocardiographs. Standardization. Paper Speed and Time Markings. Applying
Electrodes. Special Leads. Patient and Bed Aspect. Elimination of AC Interference. Routine Methods.
Grounding. Eliminating Persistent AC Interference. Protecting the ECG Machine Against Damage.
Errors and Artifacts in Recording. Lead Reversal and Lead Placement Artifacts. Wandering or Jumping
Baselines. Amplitude Artifacts. Somatic Tremor Artifacts
15. Initial Activation and the Septal Vector 101
16. Bundle Branch Block 107
Right Bundle Branch Block (RBBB). Initial QRS Vector in RBBB. Direction of Terminal QRS Vector in
RBBB. Terminal Slowing in RBBB. Complete and Incomplete RBBB. Summary of Rules for Recognizing
RBBB. RBBB Pattern. Axis in RBBB. Left Bundle Branch Block. Initial Vector in LBBB. Mid-QRS
Forces in LBBB. Terminal QRS Forces and Intrinsicoid Deflections in LBBB. Complete and Incomplete
LBBB. Summary of Criteria for LBBB. Secondary S-T, T Changes. Significance of Right and Left Bundle
Branch Block
17. Myocardial Infarction 139
General Vector Rules. Initial QRS Vector Changes. Direction of Initial Forces in Myocardial Infarction.
Pathogenesis and Recognition of Necrosis Vectors. Recognition of a Necrosis Vector in the Frontal
Plane. Recognizing Sites of Infarction by Frontal Plane Necrosis Changes. Horizontal Plane Necrosis
Changes. Anterior Infarction. Posterior Infarction. Normal Septal Versus Infarct Vectors in the
Horizontal Plane. Uncovering Hidden Necrosis Vectors. Infarction in the Presence of LBBB. LBBB
Initial Vectors Versus Infarct Vectors. Right Ventricular Overload Initial Vectors Mimicking Necrosis.
Normal Q Wave in Lead 3 Versus Inferior Infarction
18. Initial Vector Abnormalities in Preexcitation Syndromes 187
Classic Wolff-Parkinson-White Syndrome. Classifying WPW Types. Elicting the Accessory AV Bundle
Type of Preexcitation. Delta Wave Masking and Mimicking Effects. Nonatrioventricular Accessory
Bundle Preexcitation. Mahaim Fibers. James Fibers and Short P-R, Normal QRS Preexcitation
19. Terminal QRS Changes in Myocardial Infarction 203
Hemiblocks or Divisional Blocks. Anterior Divisional Blocks. Definitions of Left Axis Deviation.
Significance of left Axis Deviation. Anterior Divisional Blocks and Left Precordial S Waves. Left Axis
Deviation with No Divisional Blocks. LVH and Anterior Divisional Blocks. Congenital Heart Disease
with Possible ADBs. Posterior Divisional Blocks. Initial Vector in Divisional Blocks. Bifascicular and
Trifascicular Blocks. Bifascicular Blocks. Masquerading Bundle Branch Block. Postdivisional LBBB
and QRS Axis. Trifascicular and Quadrifascicular Blocks or Delays. Diagnosis of Divisional Blocks.
Etiologies and Prognoses of Bifascicular and Trifascicular Blocks. Lev’s Disease and Lenegre’s Disease.
Periinfarction Blocks. Imitators of Classic Periinfarction Block, or Divisional Blocks with Terminal
Slowing plus a Necrosis Vector
20. S-T Vector of Myocardial Infarction and Injury 243
Normal Repolarization Process. Genesis and Direction of the Injury Current. How the Injury Vector
Locates Infarcts. Frontal Plane Sites of Infarction. Horizontal Plane Sites. Significance of the Injury
Current. The Brugada Syndrome. Pericarditis Versus Infarction. Early Repolarization Versus
Pericarditis. Left Ventricular Hypertrophy Strain Pattern Versus an Injury Current. Digitalis S-T Vector
Versus the LVH Strain Pattern. Subendocardial Current of Injury. J Wave and Hypothermia. The
Exercise ECG. Treadmill Testing and the Master Two-Step. Methods and Purposes. Safety Measures.
Criteria for Positivity for an Ischemic S-T Response. How to Avoid False Positives. How to Avoid
False-Negative Tests for Ischemia. Vasospastic Angina Pectoris S-T Abnormalities
21. T Wave of Myocardial Infarction and Ischemia 293
Direction of the Normal T Vector. Shape and Duration of the Ischemic T. T Direction in Myocardial
Infarction. Age of Infarct. T Negativity in Pericarditis. Postextrasystolic, Post-tachycardia, and
Postpulmonary Edema T Abnormalities
Contents vii
22. Nonischemic T Abnormalities 313
Tall T Wave Differential Diagnosis. Q-T Interval. Q-T and Hypercalcemia. Q-T and T in Hypocalcemia.
U Wave. Abnormal U Waves. Negative U Waves. Relatively High U Wave. Hypokalemia and U Waves.
T Waves of Cardiomyopathies (Myocardial Infiltration, Fibrosis, Inflammation). Notched T Waves.
Digitalis Effect on the T Wave. T Wave in Hypothyroidism
23. Benign T Abnormalities and Syndromes 343
Juvenile T Pattern. Neurotic Heart T Syndrome. Hyperventilation Syndrome T Abnormalities. S-T, T
Abnormalities and the Valsalva Maneuver. Isolated T Negativity Syndrome. Benign T Negativity
of Athletes. Cerebral Autonomic T Abnormalities. Prolapsed Mitral Valve Syndrome. Suspended
Heart Syndrome. T Inversion of Schizophrenia. Summary of Maneuvers to Identify Physiologic T
Abnormalities. T Waves After Artificial Pacing
24. Left Ventricular Hypertrophy 361
Problem of Increased Voltage. Frontal Plane LVH Criteria. Horizontal Plane LVH Criteria. Secondary
LVH Criteria. Secondary Horizontal Plane LVH Criteria. LVH Strain Pattern. Other Secondary T
Criteria for LVH. Causes of Reduced Voltage. Acquired Ventricular Dilatation. Bundle Branch Block
and LVH. Significance of LVH on the ECG in Systolic Overloads. Volume Overloading of the Left
Ventricle
25. Right Ventricular Hypertrophy 397
Frontal Plane Criteria. ECG in Emphysema, or Chronic Obstructive Pulmonary Disease. Frontal Plane.
Horizontal Plane. Pectus Excavatum Versus Emphysema. Cachectic Heart Versus COPD. Summary of
the ECG Features of COPD. One or More QRS Signs. P Signs. Horizontal Plane Criteria for RVH.
Anterior QRS in RVH. Posterior QRS in RVH. R/S Ratio Regression Sign of RVH. Initial Negativity in
VI with RVH. S-T, T in the Right Precordium with RVH. Right Ventricular Systolic and Diastolic
Overloading. ECG with Systolic or Pressure Overloading. RVH of Pulmonary Stenosis. RBBB Pattern
and Right Ventricular Overloading. RVH with Acute Pulmonary Embolism. Horizontal ECG Changes in
Acute Pulmonary Embolism. Summary of Changes with Acute Pulmonary Embolism. Right Ventricular
Diastolic Overload Pattern. Combined Ventricular Overloads. Differential Diagnosis of RVH
26. Atrial Overloads 433
General Principles. Right Atrial Overload. P Axis in Right Atrial Overload. P Axis in COPD. Right
Atrial Overload. P Pulmonale. Pseudo P Pulmonale. Horizontal Plane Signs of Right Atrial Overload.
Ta Wave and P-R Segment. Left Atrial Overload. Physiology and Etiologies. Wide, Notched P Waves in
Left Atrial Overload (Intraatrial Block). P Axis in Left Atrial Overloads. Horizontal Plane Signs of Left
Atrial Overload. Left Atrial Overload in Coronary Disease. Atrial Overloads in Atrial Arrhythmias
27. Arrhythmia Diagnosis: Part 1. Nodal Abnormalities, Escape Beats, and
Premature Atrial Contractions 459
Reading Heart Rates. Arrhythmias from the Sinoatrial Node. Sinus Tachycardia and Bradycardia.
Autonomic Control of the SA Node. Sinus Arrhythmia. Natural Pacemakers and the Transmembrane
Action Potential. Phase 4 and Heart Rate. Phase 4 and Dominant Pacemakers. SA Block and Sinus
Arrest. Sinus Node Dysfunction and the Sick Sinus Syndrome. AV Block. AV Nodal Conduction
Properties. First-Degree AV Block. Laddergram. Second-Degree AV Block. Type 1. Type 2. Complete
AV Block. Pacemaker Site and Characteristics. Atria in Complete AV Block. Complete AV Block with
Acute Myocardial Infarction. Supernormal Conduction. Escape Beats. Escape Pacemakers with
Myocardial Infarction. Atrial Ectopic Beats and Pacemakers. Physiology of Automatic Cells. P Wave
Directions and Atrial Ectopic Sites. Premature Atrial Contractions. P' in Junctional and Low Atrial
Pacemakers. P'-R and P'-P Intervals. Hidden Ectopic P Wave Diagnosis. Aberrant Conduction with
Premature Atrial Contractions. Right and Left Atrial Dissociation
28. Arrhythmia Diagnosis: Part 2. Premature Ventricular Contractions,
Alternans, and Ectopic Tachycardias 515
Premature Ventricular Contractions. Site of Origin of PVCs. Timing of PVCs in the Cycle. Post-PVC
Perfect Compensatory Pause. Interpolated PVCs. Group Beating. Concealed Extrasystoles. Possible
viii Learning Electrocardiography
Causes of PVCs. Reentry Theory. Multiform Versus Multifocal PVCs. Ectopic Focus Theory. PVCs
Versus Parasystole. Parasystole Defined. Parasystole and Coupling. Parasystolic Entrance and Exit
Blocks. Parasystole and Fusion Beats. Parasystole Recognition. Reciprocal Beats. Ectopic Tachycardias.
Atrial Fibrillation. Atrial and Ventricular Rates. Characteristics of f Waves. Causes of AF. AF and
Digitalis. AF with Aberrant Conduction. Atrial Flutter. Atrial Flutter F Wave Characteristics. F
Wave-QRS Relations. Causes of Atrial Flutter. Atrial Tachycardia. Reciprocal Beat Theory for ATs.
AT in the WPW and Lown-Ganong-Levine Syndromes. AT with Block. Junctional Tachycardias.
Wandering and Shifting Atrial Pacemakers. Multifocal or Chaotic AT. Isorhythmic Dissociation.
Electrical Alternans. Ventricular Tachycardia. Mechanisms and Causes of VT. Chronic VT.
Arrhythmogenic Right Ventricular Dyslplasia (ARVD). The Brugada Syndrome. Differentiation of VT
from Supraventricular Tachycardias. AV Dissociation. Capture and Fusion Beats. Distinguishing VT
from Its Commonest Mimic, a Regular Supraventricular Tachycardia with Aberrancy: Summary.
Bidirectional Tachycardia. Ventricular Flutter and Fibrillation. Systematic Approach to Interpretation
of an Arrhythmia
29. Electronic Pacemakers 593
Fixed-Rate Pacemakers. Demand Pacemakers. Three-Letter Pacemaker Code. Pacemaker Failure.
Recognition of Implantation Site. Pacemaker Arrhythmias
30. Bundle of His Recordings 605
Technique. Intervals from the His Bundle Electrogram. Summary of What Has Been Learned or
Confirmed About the Conduction System by His Bundle Electrograms. AV Blocks. Effect of Drugs.
Bundle Branch Block and Aberrant Conduction. Preexcitation. Ectopic Pacemakers
31. Systematic Approach to Reading an Electrocardiogram 609
A Note on Describing Premature Beats or Complexes
Index 613
Preface
This book is designed for beginners and for fellows in cardiology. The two levels are
separated by placing an asterisk in front of all material that is only for the fellow. The
question and answer (Socratic) format is used because it focuses attention and also
allows one to cover up the answer and use it as programmed learning on a second
reading. Further, it requires the author to be brief and concise.
The book incorporates the author’s experience of giving brief courses to physicians,
medical students, and nurses several times a year for two decades. For example, the
book concludes with a step-by-step method of reading an electrocardiogram (ECG). This
is an invaluable aid for a student who is handed an ECG to read for the first time in an
elective program in cardiology. Similarly, at the end of the discussion of arrhythmias is a
step-by-step protocol for interpreting an arrhythmia. The hexaxial system in two planes
is used to explain directional data, so the student becomes familiar with hexaxial system
techniques by following the ECGs, most of which are mounted on a hexaxial system
diagram. The method of drawing a spatial vector has been included for instructors who
wish to show students how the electrical activity of the heart is represented on a chest
wall.
In addition to the hundreds of new references, the fourth edition has many new
diagrams and electrocardiograms. There are new explanations for such things as indeter­
minate axes, anterior QRS axes, R/S ratio progressions (normal and abnormal), the
absence of initial force changes in some patients with divisional blocks, the T negativity
in VI in newborns, and the use of multifocal versus multiform PVCs.
Also to be found are new methods of ECG diagnosis of such phenomena as infarc­
tion in the presence of left bundle branch block, posterior infarction from T waves, right
ventricular infarction, inferior infarction in the absence of a Q in lead 3 with anterior
divisional block, pericarditis from ST/T ratios and P-R segments, apical hypertrophy,
cachetic hearts, left pneumothorax, tricuspid regurgitation, right atrial overloads, and
atrial infarction.
Many new uses for electrocardiography are introduced, including how an ECG can
predict malignant hyperthermia, how to predict coronary events by treadmill testing,
how to determine the cause of left ventricular enlargement, how to test for accessory AV
pathway refractoriness, how to use simultaneous leads to diagnose divisional blocks in
difficult cases, and how to use the new pacemaker codes.
Computer analysis of electrocardiograms is probably capable of correctly reading
a perfectly normal ECG. When any abnormality is found, major disagreements may
occur in about 25% of reviewed ECGs. Without review of the ECGs by a cardiologist,
significant changes are missed.
1. Cardiac Anatomy and Physiology
A BRIEF NOTE FOR BEGINNING STUDENTS1
The heart consists of four chambers: two atria, mainly for receiving blood, and two
ventricles, mainly for pumping blood.
Diagrammatic heart Actual anatomic relations
Pulmonary veins
^Receiving
>' chambers
Aorta
^ Pumping Right and Left
chambers ventricles
The right atrium is on the anatomical right, i.e., on the right from the point of view of a
person standing facing you.
A man in the anatomical position is standing and facing you. His right is what is meant
by right in anatomy and in electrocardiography.
1 Physicians may find this section useful for giving their patients a brief background of knowledge that
explains their cardiac problems more fully.
1