Electrocardiogram in Clinical Medicine

William J. Brady, MD, is Professor of Emergency Medicine and Medicine, University of Virginia, Charlottesville, VA, USA. Michael J. Lipinski, MD, PhD, is Cardiovascular Associates of Charlottesville, Charlottesville, VA, USA. Andrew E. Darby, MD, FHRS, is Associate Professor of Cardiovascular Medicine, University of Virginia Health System, Charlottesville, VA, USA. Michael C. Bond, MD, FACEP, FAAEM, is Associate Professor of Emergency Medicine, University of Maryland School of Medicine, Baltimore, MD, USA. Nathan P. Charlton, MD, is Associate Professor of Emergency Medicine, Division of Medical Toxicology, University of Virginia, Charlottesville, VA, USA. Korin Hudson, MD, is Associate Professor of Emergency Medicine, MedStar Georgetown University Hospital, Georgetown University School of Medicine, Washington, DC, USA. Kelly Williamson, MD, is Assistant Residency Program Director, Advocate Christ Medical Center Emergency Medicine Residency; and is Clinical Associate Professor of Emergency Medicine, University of Illinois at Chicago, Chicago, IL, USA.

• List of Contributors xxiSection I The ECG in Clinical Practice 11 The ECG in Clinical Medicine 3Brian Kessen and Kelly WilliamsonIntroduction 3The ECG as a Clinical Tool 3Clinical Presentations and the ECG 4Chest Pain 4Dyspnea 5Syncope 6Toxicology 7Electrolyte Abnormalities 7Pacemakers 10Conclusion 10References 102 History of the Electrocardiogram 13Trale Permar and Kelly WilliamsonReferences 17Section II ECG Changes in Myocardial Ischemia 191 The Cardiac Action Potential and Changes in the Setting of Acute Coronary Syndrome: How Ischemia and Infarction Impacts the ECG 21Kirsti A. Campbell and Michael J. LipinskiIntroduction 21Basic Electrophysiology 21Action Potentials in Sodium-Dependent Depolarizers 21Action Potential in Calcium-Dependent Depolarizers 24Anatomy of the Electrical Conduction System 24Biochemical Impact of Ischemia 25ST-Segment Deviation 25QRS Complex 30T Waves 31P Waves 31U Waves 34Myocardial Ischemia: Causes Other than Acute Coronary Syndrome 34Conclusion 34References 362 Ischemic Electrocardiographic Changes and Correlation with Regions of the Myocardium 37Thibault Lhermusier and Michael J. LipinskiIntroduction 37Coronary Anatomy 37Definitions of STEMI and Non-ST Elevation ACS 38Left Main Coronary Ischemia 39Anterior STEMI 40Wellens Syndrome 40Inferior STEMI 41Right Ventricular Infarction 41Lateral STEMI 44Posterior STEMI 44Conduction Abnormalities in the Setting of Ischemia 46Aneurysm of the Left Ventricle 49ECG in Pharmacological and Mechanical Reperfusion 49Conclusion 50References 503 STEMI Mimics 53Peter M. PollakIntroduction 53Myocarditis and Myopericarditis 53Early Repolarization 55Left Ventricular Hypertrophy 57Prior Infarction and Ventricular Aneurysm 58Vasospasm (Prinzmetal or Variant Angina) 58Apical Ballooning Syndrome (Takotsubo Cardiomyopathy) 61Brugada Pattern and Idiopathic Ventricular Fibrillation 62Hyperkalemia 62Post-Cardioversion/Shock 62Hypothermia and Osborn Waves 62Pulmonary Embolism 63Other Causes of ST Elevation 63Conclusion 65References 654 Confounders of ST‐Elevation Myocardial Infarction 69Amy West PollakIntroduction 69Left Bundle Branch Block 69LBBB and Ischemic Heart Disease 69Left Ventricular Hypertrophy 71Ventricular Paced Rhythm 71Right Bundle Branch Block (RBBB) 73References 735 The Prognostic Value of the Electrocardiogram in Acute Coronary Syndromes 75Benjamin Shepple and Robert GibsonIntroduction 75The ECG in Acute Coronary Syndromes 75ST Elevation Myocardial Infarction (STEMI) 75The ECG during Myocardial Injury 76The ECG in Response to Therapy 80ECG after Completion of Infarction 81UA/NSTEMI 83ST-Segment Depression 83T-Wave Inversions 84Initial Normal ECG 86Arrhythmia and Conduction Disease 86Ventricular Arrhythmias 86Premature Ventricular Contractions 87Ventricular Tachycardia 87Ventricular Fibrillation 87Supraventricular Tachycardia 89AV Conduction Delay and Heart Block 90Prolonged QTc Interval 91Conclusion 92References 926 ECG Tools: Alternate Lead Placement, Serial ECGs, and ECG Monitoring 97Augustus E. Mealor, Yasir Akhtar, and Michael RagostaIntroduction 97Right-Sided Leads 97Posterior ECG 99Serial ECG Monitoring 101STM-ECG 101Serial ECG Monitoring 101References 1057 Electrocardiographic Changes of Ischemia during Stress Testing 107Michael J. Lipinski and Victor F. FroelicherIntroduction 107Exercise Physiology 108Normal ECG Changes with Exercise 108ECG Changes with Ischemia 109Women 114Diagnostic Scores 114Termination of Exercise Testing 114Exercise Testing and Acute Coronary Syndromes 117Exercise Testing after Myocardial Infarction 117Recommended Reading 120Conclusions 120References 120Section III The Dysrhythmic ECG 1231 Bradycardia 125Andrew E. DarbyIntroduction 125Abnormalities of Sinus Node Function 125Abnormalities of Atrioventricular Nodal Conduction 126Indications for Cardiac Pacing 131Conclusions 131References 1322 Atrioventricular (AV) Block 133Mark Marinescu and Andrew E. DarbyFirst-Degree AV Block 133Second-Degree AV Block 133Third-Degree AV Block 137Indications for Permanent Pacing 137Conclusions 138References 1383 The Dysrhythmic ECG: Intraventricular Block 141Andrew E. DarbyIntroduction 141Anatomy and Electrophysiology 141Right Bundle Branch Block 141Left Bundle Branch Block 143Nonspecific Intraventricular Conduction Delay 145Fascicular Block 145References 1464 Narrow QRS Complex Tachycardia 149Augustus E. Mealor and Andrew E. DarbyIntroduction 149Approach to the ECG Diagnosis of NCT 150The Regular Narrow Complex Tachycardias 151Paroxysmal Supraventricular Tachycardia 154The Irregular Narrow Complex Tachycardias 158References 1605 Wide QRS Complex Tachycardia 161Andrew E. DarbyVentricular Tachycardia 161Ventricular Paced Rhythm 164Diagnosis of Wide QRS Complex Tachycardia by Electrocardiogram 166Conclusions 167References 1676 Non-Sinus Rhythms with Normal Rates 169Will Dresen and Andrew E. DarbyIntroduction 169Ectopic Atrial Rhythm 169Accelerated Idioventricular Rhythm (AIVR) 172Conclusions 172References 1727 Rhythms of Cardiac Arrest 173Erich Kiehl and Andrew E. DarbyIntroduction 173Torsade de Pointes 174Preexcited Atrial Fibrillation 174Pulseless Electrical Activity 177Conclusions 179References 1798 Premature Atrial and Ventricular Complexes 181Adrián I. Löffler and Andrew E. DarbyPremature Atrial Contractions 181Premature Ventricular Contractions 184References 1869 Nontraditional Rhythm Disorders: Dysrhythmias Related to Metabolic and Toxicologic Conditions 187Andrew E. DarbyIntroduction 187Antiarrhythmic Drug Toxicity 188Tricyclic Antidepressant Toxicity 190Conclusions 191References 19210 Dysrhythmia-Related Syndromes 193Michele Murphy and Andrew E. DarbyIntroduction 193Dysrhythmia-Related Syndromes – Primary Electrical Abnormalities 193Wolff-Parkinson-White Syndrome 193Dysrhythmia-Related Syndromes – Primary Cardiac Structural Conditions 197Conclusions 199References 200Section IV The ECG in Cardinal Presentations and Scenarios 2011 The Patient with Cardiac Arrest 203Michael Cirone, Mitchell Lorenz, and Karis TekwaniIntroduction 203Ventricular Fibrillation 203Pulseless Ventricular Tachycardia 203Asystole 205Pulseless Electrical Activity 205Conclusion 206References 2062 The Patient with Chest Pain 207Paul Basel, Lane Thaut, and Nathan OlsonIntroduction 207Acute Coronary Syndrome 207Pericarditis 213References 2153 The Patient with Dyspnea 219Adriana Segura Olson, Anders Messersmith, and Matthew RobinsonIntroduction 219Pulmonary Embolism 219Cor Pulmonale 220Cardiomyopathy 220Congestive Heart Failure 223Pneumothorax 223ASTHMA/COPD 224Anaphylaxis/Kounis Syndrome 225Metabolic 226Summary 227References 2274 The Patient with Palpitations/Syncope 229Natasha Wheaton, Emma Nash, and Jeffrey BrownSupraventricular Tachycardia 229Atrial Fibrillation 229Multifocal Atrial Tachycardia 230Conduction Blocks 232Brugada Syndrome 233Hypertrophic Cardiomyopathy 234Wolf-Parkinson-White Syndrome 234Long QT Syndrome 236Arrhythmogenic Right Ventricular Dysplasia 237References 2375 The Patient with Preoperative Evaluation 239Sarah Chuzi, Jane Wilcox, and Lisa B. Van WagnerIntroduction 239Indications 239Common ECG Abnormalities 239Nonspecific ST-T Changes 244Pathologic Q Waves 244QT/QTc Prolongation 245Conclusion 245References 2466 The Patient in Shock 249Meagan R. Hunt and Nicholas D. HartmanIntroduction 249Cardiogenic Shock 249Obstructive Shock 252Distributive Shock 252Hypovolemic Shock 262Summary 262References 2637 The Patient with Overdose 265Ashley Pastore and Andrea CarlsonIntroduction 265Approach to the ECG in the Poisoned Patient 265Classic Toxicology ECGs 267Drug-Induced SVT 268Brugada Pattern 268Tricyclics Antidepressants 268Calcium Channel Blockers 272Conclusion 273References 274Section V The ECG in Poison, Electrolyte, Metabolic and Environmental Emergencies 2751 ECG Diagnosis and Management of the Poisoned Patient 277William F. Rushton and Christopher P. HolstegeIntroduction 277Cardiac Action Potential 277Tachycardia in the Poisoned Patient 277Bradycardia 278QRS Prolongation 279QT Prolongation 282Conclusion 283References 2842 The Use of the ECG in the Poisoned Patient: The “Rule-out Ingestion” Strategy 287Heather A. Borek and Lewis S. HardisonIntroduction 287Background 287Rate 287Rhythm 289Morphology of the Cardiac Action Potential and the ECG 290QRS Interval Prolongation 290QTc Interval Prolongation 292Timing 293The Undifferentiated Patient 294Conclusion 294References 2953 The ECG and Electrolyte Abnormalities 297Justin Rizer, Joshua D. King, and Nathan P. CharltonIntroduction 297Calcium 297Hypocalcemia 297Hypercalcemia 298Magnesium 298Hypomagnesemia 299Potassium 300Hyperkalemia 300Hypokalemia 303References 3054 The ECG and Metabolic Abnormalities 307George F. Glass, Amita Sudhir, and Amit Anil Kumar PanditIntroduction Metabolic Disturbances and the ECG 307ECG Findings During Acute Complications of Diabetes Mellitus 307Disturbances Due to Alterations of pH 309Other Metabolic Conditions 311References 3115 The ECG in Environmental Urgencies and Emergencies 315Heather T. Lounsbury and Seth O. AlthoffIntroduction 315Hypothermia 315Lightning Strikes 319Underwater Submersion 321Heat Stroke 322Conclusion 324References 324Section VI The ECG in Special Inpatient Groups 3271 The ECG-Monitored Patient 329Feras KhanIntroduction 329Clinical Scenarios Requiring Telemetry/Electrocardiographic Monitoring 329Conclusion 332References 3342 Electrocardiography in the Operating Room 335Feras KhanIntroduction 335Types of Monitoring 335Risks for Arrhythmias in the OR 335Postoperative Electrocardiographic Abnormalities 335Initial Management and ECG Evaluation 335Types of Arrhythmias 336Specific Clinical Conditions 341Conclusion 342References 3433 ECG in the ICU Patient: Identification and Treatment of Arrhythmias in the Intensive Care Unit 345Feras KhanIntroduction 345Common Dysrhythmias in the ICU 345Other Common Electrocardiographic Findings 352The Effect of Vasopressors on Cardiac Conduction 352Consequences of Anti-Arrhythmic Medications 353Arrhythmias Induced by Central Line Placement 354Specific Clinical Conditions 354Conclusion 357References 3574 The ECG in Patients with Implanted Cardiac Devices 359Ali Farzad, Benjamin J. Lawner, and Tu Carol NguyenBasics of Pacemakers 359Electrocardiographic Findings in Normally Functioning Pacemakers 360Electrocardiographic Findings in Abnormally Functioning Pacemakers 361Key Points: Electrocardiographic Clues to Pacemaker Malfunction 368Electrocardiographic Diagnosis of Acute Myocardial Infarction in the Presence of a Paced Rhythm 368Basics of the Implantable Cardioverter Defibrillator 370Electrocardiographic Findings after Defibrillation 370Basics of Left Ventricular Assist Devices 371References 3755 Electrocardiographic Manifestations of Cardiac Transplantation 377Semhar TeweldeIntroduction 377Cardiac Transplantation 377Conclusion 80Key Points 380References 380Section VII Electrocardiographic Differential Diagnosis 3831 Abnormalities of the P Wave and PR Interval 385Matthew BorlozThe Normal P Wave 385The Abnormal P Wave 385The Normal PR Interval 387The Abnormal PR Interval 387Conclusion 395References 3952 Differential Diagnosis of QRS Complex Abnormalities 397Matthew Wilson, Michael Ybarra, and Munish GoyalQRS Complex Abnormalities 397The Large QRS Complex 397The Small QRS Complex 398The Wide QRS Complex 399References 4053 Differential Diagnosis of ST Segment Changes 407Korin Hudson and Norine McGrathIntroduction 407Describing ST-Segment Changes 407Acute Coronary Syndrome and Related ST Segment Deviation 408Nonischemic Causes of ST-Segment Changes 412Benign Early Repolarization 414Acute Myocarditis/Pericarditis 415Ventricular Aneurysm 416Digitalis 416Hypothermia 417Hyperkalemia 417Brugada Syndrome 417Tachycardia-Related STD 418CNS Injury 418Other Causes 418References 4194 ECG Differential Diagnosis of T Wave and QT Interval Abnormalities 421Sanjay Shewakramani and Kari GorderThe T Wave 421Prominent T Waves 421Benign Early Repolarization 422T-Wave Inversions 422The QT Interval 427QT Prolongation 428Congenital Long QT Syndrome 429Short QT Interval 429Congenital Short QT Syndrome 429References 4295 Bradycardia 433B. Elizabeth Delasobera and Tress GoodwinBradycardia Basics 433Bradycardia Rhythms 433Rhythms That Can Be Slow 434Slow Atrial Fibrillation 435Slow Atrial Flutter 437AV Blocks 437First-Degree AV Block 438Second-Degree AV Block: Mobitz Type 1 (Wenckebach) 438Second-Degree AV Block: Mobitz Type 2 438Third-Degree or Complete Heart Block 439Conclusion 4396 Rhythms Presenting with Normal Rate 441Robert Katzer and Janet SmereckDefinitions and Clinical Considerations 441Regular Rhythms 441Irregular Rhythms 442References 4477 Narrow Complex Tachycardia 449David J. Carlberg and Rahul BhatIntroduction 449Mechanisms for NCTs 449Approach to NCT 450Sinus Node Tachycardias 453Atrial Tachycardias 453Reentrant Tachycardia Involving the AV Node 457Junctional Tachycardia 459Conclusions 459References 4608 Wide Complex Tachycardia 461Scott Young and Rachel Villacorta LyewIntroduction to Wide Complex Tachycardia 461Monomorphic WCT 461Polymorphic WCTs 468References 470Index 473