Electrical Diseases of the Heart (eBook)

Foreword 7
Contents 9
Contributors 15
Basic Foundations of Normal and Abnormal Cardiac Electrical Activity 28
The Past and Promise of Basic Cardiac Electrophysiology 29
Introduction 29
Historical Landmarks 30
Present Status of Basic Cardiac Electrophysiology 32
What Can the Cardiac Electrophysiology Community Do? 33
Summary 34
Basic Physiology of Ion Channel Function 37
Introduction Basic Principles of Cardiac 37
Electrophysiology: From Ion Channels to Ion Currents, Action Potentials, and EKG 37
Gene Correlates for Cardiac Ion Channels 43
Technologies to Explore Cardiac Cellular Electrophysiology 43
Cardiac Cellular Electrophysiology of the Human Heart 44
Cardiac Cellular Electrophysiology in Other Mammalians Computer Models of Cardiac Cellular Electrophysiology 46
Conclusion 46
Developmental Aspects of the Electrophysiology of the Heart: Function Follows Form 50
Introduction 50
Confusing Terminology 50
Early Peristaltic Hearts 51
Development of Chambered Hearts 52
T-Box Transcription Factors Regulate Compartmentalization of the Heart 53
Segregates the Left and 55
Right Ventricle, Implications for Arrhythmias? 55
Mutations in Transcription Factors Cause Congenital Heart Defects 55
Development of the Ventricular Conduction System Sarcoplasmic Reticulum and 56
Heart Development 56
Connexins and Heart Development 57
Ion Channels and Heart Development 58
Conclusion 59
Anatomic and Histopathological Characteristics of the Conductive Tissues of the Heart 63
Introduction 63
Normal Anatomy 63
Pathology 69
Neural Regulation of the Heart in Health and Disease 78
Introduction 78
Integration of Neural Control of Cardiac Electrical Activity 78
Adrenergic Influences on Cardiac Vulnerability 78
Mechanisms Responsible for Arrhythmogenesis during 80
Adrenergic Receptor Activation 80
Adrenergic Receptors 81
Sympathetic–Parasympathetic Interactions 82
Baroreflexes and Arrhythmias 82
Intrinsic Cardiac Innervation 83
Nerve Growth and Degeneration 84
Behavioral State 85
Sleep as an Autonomic Stress Test for the Heart 86
Conclusion 87
Mechanisms of Cardiac Arrhythmia 91
Introduction 91
Abnormal Impulse Formation 91
Reentrant Arrhythmias 105
Mechanisms of Action of Antiarrhythmic Drugs 159
Introduction 159
General Arrhythmia Suppression Mechanisms 161
Na Channel Blocker (Class I Drugs) 162
Drug Pathway to the Na Channel Binding Site and Modulated Receptor Hypothesis 163
Adrenergic Blocker (Class II Drugs) 166
K Channel Blocker (Class III Drugs) 166
Ca Channel Blocker (Class IV Drugs) 168
Binding Site of Ca Channel Blockers 168
Use Dependence 168
Digitalis 169
Adenosine 169
Mechanoelectrical Interactions and Their Role in Electrical Function of the Heart 171
Integrated Cardiac Electromechanics 171
Excitation–Contraction Coupling 172
Effects on the Ca Transient 175
Mechanoelectric Feedback 177
Relevance for Electrical Function of the Heart 179
Outlook 181
The Role of Cellular Sodium and Calcium Loading in Cardiac Energetics and Arrhythmogenesis: Contribution of the Late Sodium Current 187
Introduction 187
Causes of Sodium Overload 187
The Late Sodium Current 188
Consequences of an Increase 189
of Late 189
Sodium-Calcium Exchange 189
Consequences of an Increase of Intracellular Calcium 190
The Therapeutic Potential of 191
Decreasing Late 191
Sodium Ion Channelopathies 196
Introduction 196
Na Channel Structure and Function 196
Inherited Primary Electrical Disease 198
Variant Na Channels in Structural Defects 202
Acquired Cardiac Arrhythmias 205
Summary 207
L-Type Calcium Channel Disease 213
Introduction 213
L-Type Calcium Channel 213
Timothy Syndrome 215
Conclusion 218
K Channelopathies (IKs and IKr) 220
Ion Channels 220
Channels 220
Pathology 220
Channelopathy 220
Acquired or Inherited 220
K Channelopathies 221
Localization 222
Congenital Channelopathies 223
Acquired Channelopathies 229
Channelopathies of Cardiac Inwardly Rectifying Potassium Channels 233
Kir Channels and Channelopathies: An Overview 233
Inwardly Rectifying Potassium Channels in Health 234
Inwardly Rectifying Potassium Channels in Human Disease 238
Calcium Release Channels (Ryanodine Receptors) and Arrhythmogenesis 244
Introduction Excitation–Contraction Coupling in 244
the Heart 244
Cardiac Ryanodine Receptors 245
Mutations in RyR2 Linked to Cardiac Arrhythmias 247
Ryanodine Receptor Defects in Heart Failure 251
Ryanodine Receptors as a Therapeutic Target 251
Summary and Conclusions 252
Caveolae and Arrhythmogenesis 258
Introduction 258
Caveolae: Discovery 258
Caveolae: Tissue Distribution 259
Caveolae: Structure and Composition 259
Caveolins: Markers for Caveolae 260
Caveolins and Animal Models 261
Caveolins: Biochemistry 263
Caveolae: Function 264
Conclusions and Future Directions 267
Senescence and Arrhythmogenesis 273
Introduction Ventricular Arrhythmias and Sudden 273
Cardiac Death 273
Substrates for Sudden Cardiac Death in the Elderly 273
Mechanisms of Sudden Cardiac Death 274
Evaluation of Elderly Patients at Risk for Sudden Cardiac Death 275
Management of Elderly Patients at Risk for Sudden Cardiac Death 276
Other Interventions 278
Comparisons of Substrates Responsible for Atrial Versus Ventricular Fibrillation 287
Introduction 287
Biophysical Substrate 287
Ischemic Substrates 291
Congestive Heart Failure 293
Genetic Factors 295
Neuroregulatory Factors 297
Arrhythmic Remodeling 298
Conclusions 299
Single Nucleotide Polymorphisms in Health and Cardiac Disease 307
Introduction 307
Human Genome and Single Nucleotide Polymorphisms: A Revival in Genomic Medicine 307
Analysis of Single Nucleotide Polymorphisms in Arrhythmias: Toward Common Genetic Constellations for Arrhythmogenesis 309
Future Directions 313
Electrophysiological Remodeling in Dilated Cardiomyopathy and Heart Failure 316
Introduction 316
Cellular Electrophysiology of the Failing Ventricle 317
Transient Outward Potassium Current 319
Inward Rectifier Potassium Current 319
Delayed Rectifier Potassium Currents 320
ATP-Sensitive Potassium Current 320
Pacemaker Current 320
Sodium Current 320
Calcium Homeostasis 321
Sodium–Potassium Pump 323
Gap Junctions and Connexins 323
Neurohumoral Modulation of Channel/ Transporter Function in Heart Failure 324
Dyssynchronous Mechanical Activation 325
Ventricular Electrical Remodeling and Arrhythmogenesis in Heart Failure 325
Atrial Electrical Remodeling in Heart Failure 326
Conclusions 326
Ventricular Electrical Remodeling in Compensated Cardiac Hypertrophy 331
Introduction 331
Defining Electrical Remodeling in Animal Models of Left Ventricular Hypertrophy and Congestive Heart Failure 331
Aim 1. Electrical Adaptations in Hypertrophied Myocardium 334
Aim 2A. Time Course of Electrical Remodeling and Arrhythmogenesis 336
Aim 2B. Reversal of Electrical Remodeling 337
Aim 3. Electrical Remodeling: Cause or Consequence? 338
Conclusions 338
Physiological and Other Biological Pacemakers 342
Introduction 342
Pacemaker Therapy 342
Physiological Pacemakers 343
Biological Pacemakers 344
New Approaches to Biological Pacemaking 351
What Remains to Be Learned? 352
Conclusion 352
Clinical Rhythmology: Diagnostic Methods and Tools 355
Diagnostic Electrocardiography 357
Introduction 357
Case 1 357
Case 2 361
Case 3 366
Concluding Remarks 367
Ambulatory Monitoring (Holter, Event Recorders, External, and Implantable Loop Recorders and Wireless Technology) 370
Introduction 370
Holter Monitoring 370
Transtelephonic Monitors and External Loop Recorders 371
Implantable Loop Recorders 373
When to Choose Prolonged Monitoring 377
Conclusion 377
Signal Averaged Electrocardiogram 379
Introduction 379
Technical Aspects of the Signal Averaged Electrocardiogram 379
Clinical Applications of the Signal Averaged Electrocardiogram 381
Miscellaneous Applications 387
Conclusions 387
Surface Mapping and Magnetoelectrocardiography 405
Introduction 405
Basic Principles of Magnetocardiograms 405
Clinical Utility for Detecting High-Risk Patients for Sudden Cardiac Death 410
Future Direction of Magnetocardiograms 416
Body Surface Potential Mappings 417
Microvolt T Wave Alternans: Mechanisms and Implications for Prediction of Sudden Cardiac Death 420
Introduction 420
Definition and History of T Wave Alternans 420
Basic Cellular Mechanisms of Repolarization Alternans 421
Mechanism Linking Repolarization Alternans to the Genesis of Arrhythmias 423
Measurement of T Wave Alterans in Patients 425
Clinical Utility of T Wave Alternans 428
Limitations of the T Wave Alternans Test 429
Effect of Medications on T Wave Alternans Testing 430
Provocative Testing in Inherited Arrhythmias 450
Introduction 450
Congenital Long QT Syndrome 450
Brugada Syndrome 454
Novel Predictors of Sudden Cardiac Death 460
Introduction Left Ventricular Dysfunction and 460
Sudden Cardiac Death in the General Population 460
Other Known Predictors of Sudden Cardiac Death 461
Prolonged Ventricular Repolarization 461
Diabetes Mellitus 461
Left Ventricular Hypertrophy 462
Obesity 463
Socioeconomic Status and Sudden Cardiac Death 463
Genetic Contributions to Sudden Cardiac Death 464
Summary and Conclusions 465
Genetic Testing 470
Introduction 470
Primer on Molecular Genetics 471
Techniques Used in Genetic Testing at the Single Gene Level 477
Genetic Testing in Electrical Diseases of the Heart and Sudden Cardiac Death 481
Family Matters: Ethical, Legal, and Societal Implications 483
Conclusions 483
Heritable Cardiac Channelopathies, Primary Electrical Diseases, and Clinical Syndromes 485
Celebrating the Challenge of Cardiac Arrhythmias 487
Congenital Long QT Syndrome 488
Introduction 488
Case Vignettes 488
Historical Background 489
Epidemiology and Prevalence 489
Molecular Genetics 490
Clinical Presentations 490
Genotype–Phenotype-Specific Correlations 491
Diagnostic Evaluation 492
Management 497
Case Vignettes Revisited 504
Brugada Syndrome: Clinical and Genetic Aspects 509
Introduction 509
General Clinical Properties 511
Genetic Aspects 511
Electrocardiographic Characteristics 512
Structural Abnormalities 516
Differential Diagnosis in Brugada Syndrome 517
Therapy 517
Risk Stratification 517
Summary 518
Brugada Syndrome: Cellular Mechanisms and Approaches to Therapy 526
Introduction 526
Brugada Syndrome 526
Sex-Related Differences in the Manifestation of the Brugada Syndrome 542
Approach to Therapy 544
Catecholaminergic Polymorphic Ventricular Tachycardia 562
Introduction 562
Genetics 562
Pathophysiology 563
Clinical Management 566
Andersen–Tawil and Timothy Syndromes 571
Introduction 571
Andersen–Tawil Syndrome 571
Timothy Syndrome 574
Summary 577
Short QT Syndrome 580
Introduction 580
Definition and Terminology 580
History and Incidence 584
Genetics, Etiology, and Mechanism 584
Electrophysiological Findings 585
Clinical Manifestations and Clinical Course 585
Treatment Concluding Remarks 587
Progressive Cardiac Conduction Disease 590
Introduction First Description of Cardiac Conduction Defect 590
Cardiac Conduction Defect a Genetic Disease? 591
Other Familial Forms of Cardiac Conduction Defects Linked to 596
Mutations 596
Conduction Defects in Other Syndromes 598
Lene` gre Disease and Brugada Syndrome: An Overlap Syndrome? 598
Conclusions 600
Familial Atrial Fibrillation and Standstill 603
Introduction 603
Atrial Fibrillation Without Structural Heart Disease 603
Genetic Aspects of Atrial Fibrillation in Acquired Structural Heart Disease 606
Atrial Standstill 608
Conclusions 610
Idiopathic Ventricular Fibrillation 614
Introduction 614
History 614
Etiology Clinical Manifestations 615
Electrocardiogram 616
Electrophysiologic Data 617
Diagnosis 619
Differential Diagnosis 620
Prognosis and Therapy of Idiopathic Ventricular Fibrillation 622
Secondary Hereditary Electrical Diseases and Clinical Syndromes 631
Cardiac Remodeling 633
Arrhythmogenic Malignancies in Hypertrophic Cardiomyopathy 636
Introduction 636
Definition 636
Nomenclature 636
Epidemiology of Hypertrophic Cardiomyopathy and Sudden Cardiac Death 636
Pathology/Pathophysiology/ Pathogenetics of Hypertrophic Cardiomyopathy 638
Clinical Presentation of Hypertrophic Cardiomyopathy 640
Diagnosis of Hypertrophic Cardiomyopathy 641
Sudden Cardiac Death Risk Stratification in Hypertrophic Cardiomyopathy 641
Clinical Management of Hypertrophic Cardiomyopathy 645
The Interaction between Athletics and Hypertrophic Cardiomyopathy 647
Family Screening in Hypertrophic Cardiomyopathy 648
Sudden Death in Dilated Cardiomyopathy and Skeletal Myopathies 653
Introduction 653
Dilated Cardiomyopathy 653
Skeletal Myopathies 656
Conclusions 663
Ventricular Arrhythmias in Right Ventricular Dysplasia/ Cardiomyopathy 669
Introduction 669
Clinical Presentation and Natural History 669
Diagnosis of Arrhythmogenic Right Ventricular Dysplasia/ Cardiomyopathy 670
Electrocardiographic Evaluation 670
Imaging of the Right Ventricle 672
Myocardial Biopsy 672
Differential Diagnosis 673
Histopathology and Etiology 674
Genetics 674
Management and Use of Implantable Defibrillators 676
Unanswered Questions 677
The Wolff–Parkinson–White Syndrome and the Risk of Sudden Death 680
History 680
Unusual Variations of Accessory Atrioventricular Connections in Wolff – Parkinson – White Syndrome 680
Wolff–Parkinson–White and Congenital Heart Disease 685
Genetics and Wolff–Parkinson–White 685
Wolff–Parkinson–White and the Risk of Sudden Cardiac Death 688
Clinical Management of Wolff – Parkinson – White 690
Iatrogenic (Drug-Induced) Cardiac Channelopathies and Sudden Cardiac Death 697
Drug-Induced Enhanced Risk for Sudden Cardiac Death in Clinical Practice, Clinical Research, and Drug Development 699
Introduction 699
Regulatory Focus on Cardiac Safety 699
The Thorough Electrocardiographic Trial 700
Pharmacogenomics in Drug Development and Clinical Research 703
Introduction 703
Genetics of Cardiac Repolarization 704
Overview of Pharmacogenetics 705
Genetics of Drug-Induced QT Prolongation 707
Outlook 712
Mechanisms of Drug-Induced Cardiac Toxicity 717
Introduction 717
Drug-Induced QT Prolongation and Proarrhythmia 717
Mechanism of Cardiac Toxicity Induced by Na Channel Blockers 721
Digitalis Intoxication 725
Summary 726
Acquired (Drug-Induced) Long QT Syndrome 731
Introduction 731
Drug-Induced Cardiovascular Toxicity 731
Acquired Cardiac Channelopathies, Ion Remodeling, and Repolarization Reserve 737
Acquired Drug-Induced Long QT Syndrome: Clinical, Electrophysiological, and Electrocardiographic Considerations 738
Acquired Drug-Induced Long QT Syndrome and Its Implication for Clinical Reasearch and Drug Development: Regulatory and Statistical Considerations 741
Acquired Form of Brugada Syndrome 745
Brugada Syndome 745
Acquired Form of Brugada Syndrome 747
Treatment Modalities 755
Treatment Modalities 757
Clinical Role of Antiarrhythmic Drugs in the Prevention of Sudden Death 759
Introduction Historical Perspectives 759
Use of Antiarrhythmic Drugs in the Prevention of Sudden Cardiac Death 768
Use of Antiarrhythmic Drugs as an Adjunct to Implantable Cardioverter Defibrillator Therapy 771
Other Considerations 775
Summary 777
Nonantiarrhythmic Drugs in Sudden Death Prevention 786
Introduction 786
Pathophysiology 786
Blockers 787
Renin–Angiotensin– Aldosterone System 789
Modulators of Cholesterol and Inflammation 791
Conclusions 793
The Implantable Cardioverter Defibrillator: Technical and Clinical Considerations 798
Introduction 798
Indications 798
Technical Aspects of Implantable Cardioverter Defibrillators 800
Summary 804
Beyond Sudden Death Prevention: Minimizing Implantable Cardioverter Defibrillator Shocks and Morbidity and Optimizing Efficacy 807
Introduction 807
Minimizing Shocks for Nonsustained Ventricular Arrhythmias 807
Adjunctive Therapies to Prevent Ventricular Arrhythmias 810
Minimizing Inappropriate Shocks: Sustained Ventricular Tachycardia Discrimination 812
Pacing Morbidity: Minimizing Right Ventricular Pacing 819
Conclusion 821
Pacing and Cardiac Resynchronization 827
Introduction 827
Studies of Cardiac Resynchronization Therapy Pacing 827
Studies of Cardiac Resynchronization Therapy Defibrillator 830
Meta-Analysis of Cardiac Resynchronization Therapy 831
Why Is It Difficult to Show an Effect of Cardiac Resynchronization Therapy on Sudden Cardiac Death? 831
The Future of Cardiac Resynchronization Therapy 833
Device Therapy for Remote Patient Management 835
Introduction 835
Current Uses and Goals for the Future 836
The History of Monitoring 837
Current Examples of Remote Monitoring 837
Conclusions 850
Catheter Ablation of Ventricular Tachycardia and Fibrillation 852
Introduction Mapping and Ablation Procedure 852
Various Substrates Associated with Ventricular Fibrillation 854
Conclusions 862
Surgical Treatment of Atrial Fibrillation 865
Introduction 865
Indications 865
Techniques 865
Postoperative Management 867
Outcomes 868
The Cox-Maze Procedure and Mitral Valve Surgery 869
Tachycardia-Induced Cardiomyopathy 870
Atrial Arrhythmias in Congenital Heart Disease 871
Atrial Fibrillation and Hypertrophic Cardiomyopathy 872
Future Perspectives 872
Risk Stratification and Prevention of Sudden Cardiac Death in Acquired Clinical Conditions 875
Screening for Risk of Sudden Cardiac Death 877
Clinical Trials in Sudden Cardiac Death Prevention: Principles and Endpoints 879
Risk Stratification for Sudden Death in Patients with Coronary Artery Disease 884
Introduction 884
Clinical Factors: Value of the History 886
Standard 12-Lead Electrocardiogram 886
Left Ventricular Ejection Fraction 887
Spontaneous Ventricular Ectopy and Nonsustained Ventricular Tachycardia 887
Signal-Averaged Electrocardiography 888
Electrophysiological Testing ( Programmed Electrical Stimulation) 888
T Wave Alternans 889
Measures of Abnormalities in Autonomic Nervous System Tone 890
Summary 892
Heart Failure and Sudden Death 899
Introduction 899
Death Mode in Advanced Stage of Heart Failure 899
Mechanisms of Sudden Death in Heart Failure 901
Identifying Patients with Increased Risk of Sudden Death 904
Prevention of Sudden Death 906
Summary and Conclusions 909
Neurological Conditions and Sudden Death 914
Introduction 914
Definition of Sudden Unexplained or Unexpected Death in Epilepsy Historical Recognition of Sudden Unexplained or Unexpected Death 914
in Epilepsy 914
Incidence of Sudden Unexplained or Unexpected Death in Epilepsy 915
Risk Factors of Sudden Unexplained or Unexpected Death in Epilepsy 916
Potential Cardiac Mechanisms in Sudden Unexplained or Unexpected Death in Epilepsy 917
Other Possible Mechanisms in Sudden Unexplained or Unexpected Death in Epilepsy 918
Comments Regarding Sudden Unexplained or Unexpected Death in Epilepsy 919
Sudden Cardiac Death in Other Neurological Conditions 919
Conclusions 920
Obstructive Sleep Apnea and Sudden Death 924
Introduction 924
Epidemiology of Obstructive Sleep Apnea 924
Physiology of Normal Sleep 924
Pathophysiology of Sleep in Obstructive Sleep Apnea 926
Obstructive Sleep Apnea and Potential Mechanisms of Sudden Death 927
Associations between Obstructive Sleep Apnea and Sudden Death 930
Conclusions 932
Sudden Cardiac Death in Athletes 937
Introduction Epidemiological Profile of Sudden 937
Cardiac Death in Athletes 937
Causes of Sudden Cardiac Death in the Athlete 938
Risk of Sudden Cardiac Death During Sports 943
Preparticipation Screening for Prevention of Sudden CardiacDeath 944
Athletic Participation 945
Early Defibrillation Program 946
Sudden Cardiac Death in Infancy: Focus on Prolonged Repolarization 950
Introduction 950
The QT Hypothesis 950
The Italian Study on Neonatal Electrocardiograms and Sudden Infant Death Syndrome 951
The Molecular Link 951
Sudden Cardiac Death in Kidney Diseases 960
Introduction 960
Possible Mechanisms 960
Risk Factors and Risk Stratification 962
Prevention of Sudden Cardiac Death and Future Directions 965
Index 969