Electrocardiogram in Clinical Medicine

List of Contributors xxi Section I The ECG in Clinical Practice 1 1 The ECG in Clinical Medicine 3 Brian Kessen and Kelly Williamson Introduction 3 The ECG as a Clinical Tool 3 Clinical Presentations and the ECG 4 Chest Pain 4 Dyspnea 5 Syncope 6 Toxicology 7 Electrolyte Abnormalities 7 Pacemakers 10 Conclusion 10 References 10 2 History of the Electrocardiogram 13 Trale Permar and Kelly Williamson References 17 Section II ECG Changes in Myocardial Ischemia 19 1 The Cardiac Action Potential and Changes in the Setting of Acute Coronary Syndrome: How Ischemia and Infarction Impacts the ECG 21 Kirsti A. Campbell and Michael J. Lipinski Introduction 21 Basic Electrophysiology 21 Action Potentials in Sodium-Dependent Depolarizers 21 Action Potential in Calcium-Dependent Depolarizers 24 Anatomy of the Electrical Conduction System 24 Biochemical Impact of Ischemia 25 ST-Segment Deviation 25 QRS Complex 30 T Waves 31 P Waves 31 U Waves 34 Myocardial Ischemia: Causes Other than Acute Coronary Syndrome 34 Conclusion 34 References 36 2 Ischemic Electrocardiographic Changes and Correlation with Regions of the Myocardium 37 Thibault Lhermusier and Michael J. Lipinski Introduction 37 Coronary Anatomy 37 Definitions of STEMI and Non-ST Elevation ACS 38 Left Main Coronary Ischemia 39 Anterior STEMI 40 Wellens Syndrome 40 Inferior STEMI 41 Right Ventricular Infarction 41 Lateral STEMI 44 Posterior STEMI 44 Conduction Abnormalities in the Setting of Ischemia 46 Aneurysm of the Left Ventricle 49 ECG in Pharmacological and Mechanical Reperfusion 49 Conclusion 50 References 50 3 STEMI Mimics 53 Peter M. Pollak Introduction 53 Myocarditis and Myopericarditis 53 Early Repolarization 55 Left Ventricular Hypertrophy 57 Prior Infarction and Ventricular Aneurysm 58 Vasospasm (Prinzmetal or Variant Angina) 58 Apical Ballooning Syndrome (Takotsubo Cardiomyopathy) 61 Brugada Pattern and Idiopathic Ventricular Fibrillation 62 Hyperkalemia 62 Post-Cardioversion/Shock 62 Hypothermia and Osborn Waves 62 Pulmonary Embolism 63 Other Causes of ST Elevation 63 Conclusion 65 References 65 4 Confounders of ST‐Elevation Myocardial Infarction 69 Amy West Pollak Introduction 69 Left Bundle Branch Block 69 LBBB and Ischemic Heart Disease 69 Left Ventricular Hypertrophy 71 Ventricular Paced Rhythm 71 Right Bundle Branch Block (RBBB) 73 References 73 5 The Prognostic Value of the Electrocardiogram in Acute Coronary Syndromes 75 Benjamin Shepple and Robert Gibson Introduction 75 The ECG in Acute Coronary Syndromes 75 ST Elevation Myocardial Infarction (STEMI) 75 The ECG during Myocardial Injury 76 The ECG in Response to Therapy 80 ECG after Completion of Infarction 81 UA/NSTEMI 83 ST-Segment Depression 83 T-Wave Inversions 84 Initial Normal ECG 86 Arrhythmia and Conduction Disease 86 Ventricular Arrhythmias 86 Premature Ventricular Contractions 87 Ventricular Tachycardia 87 Ventricular Fibrillation 87 Supraventricular Tachycardia 89 AV Conduction Delay and Heart Block 90 Prolonged QTc Interval 91 Conclusion 92 References 92 6 ECG Tools: Alternate Lead Placement, Serial ECGs, and ECG Monitoring 97 Augustus E. Mealor, Yasir Akhtar, and Michael Ragosta Introduction 97 Right-Sided Leads 97 Posterior ECG 99 Serial ECG Monitoring 101 STM-ECG 101 Serial ECG Monitoring 101 References 105 7 Electrocardiographic Changes of Ischemia during Stress Testing 107 Michael J. Lipinski and Victor F. Froelicher Introduction 107 Exercise Physiology 108 Normal ECG Changes with Exercise 108 ECG Changes with Ischemia 109 Women 114 Diagnostic Scores 114 Termination of Exercise Testing 114 Exercise Testing and Acute Coronary Syndromes 117 Exercise Testing after Myocardial Infarction 117 Recommended Reading 120 Conclusions 120 References 120 Section III The Dysrhythmic ECG 123 1 Bradycardia 125 Andrew E. Darby Introduction 125 Abnormalities of Sinus Node Function 125 Abnormalities of Atrioventricular Nodal Conduction 126 Indications for Cardiac Pacing 131 Conclusions 131 References 132 2 Atrioventricular (AV) Block 133 Mark Marinescu and Andrew E. Darby First-Degree AV Block 133 Second-Degree AV Block 133 Third-Degree AV Block 137 Indications for Permanent Pacing 137 Conclusions 138 References 138 3 The Dysrhythmic ECG: Intraventricular Block 141 Andrew E. Darby Introduction 141 Anatomy and Electrophysiology 141 Right Bundle Branch Block 141 Left Bundle Branch Block 143 Nonspecific Intraventricular Conduction Delay 145 Fascicular Block 145 References 146 4 Narrow QRS Complex Tachycardia 149 Augustus E. Mealor and Andrew E. Darby Introduction 149 Approach to the ECG Diagnosis of NCT 150 The Regular Narrow Complex Tachycardias 151 Paroxysmal Supraventricular Tachycardia 154 The Irregular Narrow Complex Tachycardias 158 References 160 5 Wide QRS Complex Tachycardia 161 Andrew E. Darby Ventricular Tachycardia 161 Ventricular Paced Rhythm 164 Diagnosis of Wide QRS Complex Tachycardia by Electrocardiogram 166 Conclusions 167 References 167 6 Non-Sinus Rhythms with Normal Rates 169 Will Dresen and Andrew E. Darby Introduction 169 Ectopic Atrial Rhythm 169 Accelerated Idioventricular Rhythm (AIVR) 172 Conclusions 172 References 172 7 Rhythms of Cardiac Arrest 173 Erich Kiehl and Andrew E. Darby Introduction 173 Torsade de Pointes 174 Preexcited Atrial Fibrillation 174 Pulseless Electrical Activity 177 Conclusions 179 References 179 8 Premature Atrial and Ventricular Complexes 181 Adrián I. Löffler and Andrew E. Darby Premature Atrial Contractions 181 Premature Ventricular Contractions 184 References 186 9 Nontraditional Rhythm Disorders: Dysrhythmias Related to Metabolic and Toxicologic Conditions 187 Andrew E. Darby Introduction 187 Antiarrhythmic Drug Toxicity 188 Tricyclic Antidepressant Toxicity 190 Conclusions 191 References 192 10 Dysrhythmia-Related Syndromes 193 Michele Murphy and Andrew E. Darby Introduction 193 Dysrhythmia-Related Syndromes – Primary Electrical Abnormalities 193 Wolff-Parkinson-White Syndrome 193 Dysrhythmia-Related Syndromes – Primary Cardiac Structural Conditions 197 Conclusions 199 References 200 Section IV The ECG in Cardinal Presentations and Scenarios 201 1 The Patient with Cardiac Arrest 203 Michael Cirone, Mitchell Lorenz, and Karis Tekwani Introduction 203 Ventricular Fibrillation 203 Pulseless Ventricular Tachycardia 203 Asystole 205 Pulseless Electrical Activity 205 Conclusion 206 References 206 2 The Patient with Chest Pain 207 Paul Basel, Lane Thaut, and Nathan Olson Introduction 207 Acute Coronary Syndrome 207 Pericarditis 213 References 215 3 The Patient with Dyspnea 219 Adriana Segura Olson, Anders Messersmith, and Matthew Robinson Introduction 219 Pulmonary Embolism 219 Cor Pulmonale 220 Cardiomyopathy 220 Congestive Heart Failure 223 Pneumothorax 223 ASTHMA/COPD 224 Anaphylaxis/Kounis Syndrome 225 Metabolic 226 Summary 227 References 227 4 The Patient with Palpitations/Syncope 229 Natasha Wheaton, Emma Nash, and Jeffrey Brown Supraventricular Tachycardia 229 Atrial Fibrillation 229 Multifocal Atrial Tachycardia 230 Conduction Blocks 232 Brugada Syndrome 233 Hypertrophic Cardiomyopathy 234 Wolf-Parkinson-White Syndrome 234 Long QT Syndrome 236 Arrhythmogenic Right Ventricular Dysplasia 237 References 237 5 The Patient with Preoperative Evaluation 239 Sarah Chuzi, Jane Wilcox, and Lisa B. Van Wagner Introduction 239 Indications 239 Common ECG Abnormalities 239 Nonspecific ST-T Changes 244 Pathologic Q Waves 244 QT/QTc Prolongation 245 Conclusion 245 References 246 6 The Patient in Shock 249 Meagan R. Hunt and Nicholas D. Hartman Introduction 249 Cardiogenic Shock 249 Obstructive Shock 252 Distributive Shock 252 Hypovolemic Shock 262 Summary 262 References 263 7 The Patient with Overdose 265 Ashley Pastore and Andrea Carlson Introduction 265 Approach to the ECG in the Poisoned Patient 265 Classic Toxicology ECGs 267 Drug-Induced SVT 268 Brugada Pattern 268 Tricyclics Antidepressants 268 Calcium Channel Blockers 272 Conclusion 273 References 274 Section V The ECG in Poison, Electrolyte, Metabolic and Environmental Emergencies 275 1 ECG Diagnosis and Management of the Poisoned Patient 277 William F. Rushton and Christopher P. Holstege Introduction 277 Cardiac Action Potential 277 Tachycardia in the Poisoned Patient 277 Bradycardia 278 QRS Prolongation 279 QT Prolongation 282 Conclusion 283 References 284 2 The Use of the ECG in the Poisoned Patient: The “Rule-out Ingestion” Strategy 287 Heather A. Borek and Lewis S. Hardison Introduction 287 Background 287 Rate 287 Rhythm 289 Morphology of the Cardiac Action Potential and the ECG 290 QRS Interval Prolongation 290 QTc Interval Prolongation 292 Timing 293 The Undifferentiated Patient 294 Conclusion 294 References 295 3 The ECG and Electrolyte Abnormalities 297 Justin Rizer, Joshua D. King, and Nathan P. Charlton Introduction 297 Calcium 297 Hypocalcemia 297 Hypercalcemia 298 Magnesium 298 Hypomagnesemia 299 Potassium 300 Hyperkalemia 300 Hypokalemia 303 References 305 4 The ECG and Metabolic Abnormalities 307 George F. Glass, Amita Sudhir, and Amit Anil Kumar Pandit Introduction Metabolic Disturbances and the ECG 307 ECG Findings During Acute Complications of Diabetes Mellitus 307 Disturbances Due to Alterations of pH 309 Other Metabolic Conditions 311 References 311 5 The ECG in Environmental Urgencies and Emergencies 315 Heather T. Lounsbury and Seth O. Althoff Introduction 315 Hypothermia 315 Lightning Strikes 319 Underwater Submersion 321 Heat Stroke 322 Conclusion 324 References 324 Section VI The ECG in Special Inpatient Groups 327 1 The ECG-Monitored Patient 329 Feras Khan Introduction 329 Clinical Scenarios Requiring Telemetry/Electrocardiographic Monitoring 329 Conclusion 332 References 334 2 Electrocardiography in the Operating Room 335 Feras Khan Introduction 335 Types of Monitoring 335 Risks for Arrhythmias in the OR 335 Postoperative Electrocardiographic Abnormalities 335 Initial Management and ECG Evaluation 335 Types of Arrhythmias 336 Specific Clinical Conditions 341 Conclusion 342 References 343 3 ECG in the ICU Patient: Identification and Treatment of Arrhythmias in the Intensive Care Unit 345 Feras Khan Introduction 345 Common Dysrhythmias in the ICU 345 Other Common Electrocardiographic Findings 352 The Effect of Vasopressors on Cardiac Conduction 352 Consequences of Anti-Arrhythmic Medications 353 Arrhythmias Induced by Central Line Placement 354 Specific Clinical Conditions 354 Conclusion 357 References 357 4 The ECG in Patients with Implanted Cardiac Devices 359 Ali Farzad, Benjamin J. Lawner, and Tu Carol Nguyen Basics of Pacemakers 359 Electrocardiographic Findings in Normally Functioning Pacemakers 360 Electrocardiographic Findings in Abnormally Functioning Pacemakers 361 Key Points: Electrocardiographic Clues to Pacemaker Malfunction 368 Electrocardiographic Diagnosis of Acute Myocardial Infarction in the Presence of a Paced Rhythm 368 Basics of the Implantable Cardioverter Defibrillator 370 Electrocardiographic Findings after Defibrillation 370 Basics of Left Ventricular Assist Devices 371 References 375 5 Electrocardiographic Manifestations of Cardiac Transplantation 377 Semhar Tewelde Introduction 377 Cardiac Transplantation 377 Conclusion 80 Key Points 380 References 380 Section VII Electrocardiographic Differential Diagnosis 383 1 Abnormalities of the P Wave and PR Interval 385 Matthew Borloz The Normal P Wave 385 The Abnormal P Wave 385 The Normal PR Interval 387 The Abnormal PR Interval 387 Conclusion 395 References 395 2 Differential Diagnosis of QRS Complex Abnormalities 397 Matthew Wilson, Michael Ybarra, and Munish Goyal QRS Complex Abnormalities 397 The Large QRS Complex 397 The Small QRS Complex 398 The Wide QRS Complex 399 References 405 3 Differential Diagnosis of ST Segment Changes 407 Korin Hudson and Norine McGrath Introduction 407 Describing ST-Segment Changes 407 Acute Coronary Syndrome and Related ST Segment Deviation 408 Nonischemic Causes of ST-Segment Changes 412 Benign Early Repolarization 414 Acute Myocarditis/Pericarditis 415 Ventricular Aneurysm 416 Digitalis 416 Hypothermia 417 Hyperkalemia 417 Brugada Syndrome 417 Tachycardia-Related STD 418 CNS Injury 418 Other Causes 418 References 419 4 ECG Differential Diagnosis of T Wave and QT Interval Abnormalities 421 Sanjay Shewakramani and Kari Gorder The T Wave 421 Prominent T Waves 421 Benign Early Repolarization 422 T-Wave Inversions 422 The QT Interval 427 QT Prolongation 428 Congenital Long QT Syndrome 429 Short QT Interval 429 Congenital Short QT Syndrome 429 References 429 5 Bradycardia 433 B. Elizabeth Delasobera and Tress Goodwin Bradycardia Basics 433 Bradycardia Rhythms 433 Rhythms That Can Be Slow 434 Slow Atrial Fibrillation 435 Slow Atrial Flutter 437 AV Blocks 437 First-Degree AV Block 438 Second-Degree AV Block: Mobitz Type 1 (Wenckebach) 438 Second-Degree AV Block: Mobitz Type 2 438 Third-Degree or Complete Heart Block 439 Conclusion 439 6 Rhythms Presenting with Normal Rate 441 Robert Katzer and Janet Smereck Definitions and Clinical Considerations 441 Regular Rhythms 441 Irregular Rhythms 442 References 447 7 Narrow Complex Tachycardia 449 David J. Carlberg and Rahul Bhat Introduction 449 Mechanisms for NCTs 449 Approach to NCT 450 Sinus Node Tachycardias 453 Atrial Tachycardias 453 Reentrant Tachycardia Involving the AV Node 457 Junctional Tachycardia 459 Conclusions 459 References 460 8 Wide Complex Tachycardia 461 Scott Young and Rachel Villacorta Lyew Introduction to Wide Complex Tachycardia 461 Monomorphic WCT 461 Polymorphic WCTs 468 References 470 Index 473