MANAGEMENT OF CARDIAC ARRHYTHMIAS.

Description

Contents Contributors Part I: Basic Principles of Cardiac Electrophysiology and Pharmacology 1: Basic Principles of Cardiac Electrophysiology Introduction Resting Membrane Potential Ion Channels Sodium Ion Channels Structure Nomenclature and Family of Nav Channels Voltage-Gated Sodium Ion Channels Calcium Ion Channels Structure Nomenclature and Family of CaV L-Type (CaV1.x) and T-Type (CaV3.x) Channels Potassium Ion Channels Cardiac Potassium Channels Voltage-Gated Potassium Channel Structure Voltage-Gated Potassium Channel Currents Inwardly Rectifying Potassium Channel Structure Inwardly Rectifying Potassium Currents Cardiac Action Potential Action Potential Duration and Effective Refractory Period (ERP) Sinoatrial Node and Atrioventricular Node Electrophysiology Regional Differences in Action Potential Transmural Differences in Ventricular Action Potential Calcium Handling Cardiac Conduction Wavelength Arrhythmias References 2: Mechanisms Underlying the Development of Cardiac Arrhythmias Introduction Abnormal Impulse Formation Normal Automaticity The Voltage and Calcium Clocks Subsidiary Pacemakers Automaticity as a Mechanism of Cardiac Arrhythmia Hereditary Bradycardia Secondary SA Node Dysfunction Enhanced Automaticity Overdrive Suppression of Automaticity Parasystole and Modulated Parasystole Afterdepolarization and Triggered Activity Early Afterdepolarization-Induced Triggered Activity Cellular Origin of Early Afterdepolarizations Ionic Mechanisms Responsible for the EAD Delayed Afterdepolarization (DAD)-Induced Triggered Activity Role of Delayed Afterdepolarization-Induced Triggered Activity in the Development of Cardiac Arrhythmias Late Phase 3 Early Afterdepolarizations and Their Role in the Initiation of Fibrillation Afterdepolarization-Induced Triggered Activity in Ventricles Versus Atria Reentrant Arrhythmias Circus Movement Reentry Around an Anatomical Obstacle Circus Movement Reentry Without an Anatomical Obstacle Fibrillation: Reentry Versus Wannabe Reentry? Figure-Eight Reentry Reflection Phase 2 Reentry Spatial Dispersion of Repolarization Structural Remodeling and Arrhythmias Mechanisms Underlying Ventricular Arrhythmias J Wave Syndromes Brugada Syndrome The Long QT Syndrome Short QT Syndrome Catecholaminergic Polymorphic Ventricular Tachycardia The Role of Spatial Dispersion of Repolarization in Development of Life-Threatening Arrhythmias References 3: Genetic and Molecular Basis of Cardiac Arrhythmias Introduction Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) Congenital Long QT Syndrome (LQTS) Brugada Syndrome (BrS) Familial Atrial Fibrillation (AF) Conclusions References 4: Unique Rhythm Phenomena and Mechanisms Introduction Two Cell Types Slow-Response Myocytes Fast-Response Myocytes Determinants of Threshold Potential Excitability Postrepolarization Refractoriness (PRR) Ashman Phenomenon Cardiac Memory Phase 3 Block Phase 4 Block Inverse Wenckebach Concealed Conduction Potential Mechanisms of Concealed Conduction That Leads to Conduction Block [21–23] ECG Manifestations of the Subsequent Impulse Following Concealed Conduction Gap Phenomenon Supernormal Conduction Linking Phenomenon Wedensky Phenomenon References 5: ECG Waves and Signs: Ionic and Cellular Basis Introduction Establishment of the Standard 12-Lead ECG Key ECG Concepts Instantaneous Mean Electrical Vector Mean Electrical Axis Ionic and Cellular Basis of the Normal 12-Lead ECG The P Wave The PR Segment and PR Interval The QRS Complex The ST Segment and T Wave The U Wave The QT Interval The Abnormal 12-Lead ECG QRS Axis Deviations Bundle Branch and Fascicular Blocks Right Bundle Branch Block (RBBB) Left Bundle Branch Block (LBBB) ECG Changes in Bundle Branch and Fascicular Blocks: General Rules ECG Changes Attending Transmural Myocardial Ischemia ECG Changes Associated with the J Wave Syndromes References 6: Mechanisms of Action of Antiarrhythmic Drugs Introduction Class I Antiarrhythmic Drugs Cardiac Sodium (Na+) Channel Postrepolarization Refractoriness (PRR) Use Dependence of Class I Antiarrhythmic Drugs Mechanism of Antiarrhythmia of Class I Antiarrhythmic Drug Inhibition of Reentry Inhibition of Triggered Activity Reduction of Repolarization Heterogeneity Proarrhythmia of Class I Antiarrhythmic Drugs Class II Antiarrhythmic Drugs Inhibition of Sympathetic Hyperactivity Inhibition of Structural and Electrical Remodeling Inhibition of Ion Channels Role in Inherited Arrhythmogenic Diseases Class III Antiarrhythmic Drugs Antiarrhythmic Mechanism for Reentrant Arrhythmias Reverse-Use Dependence of Class III Antiarrhythmic Drugs Class IV Antiarrhythmic Drugs References Part II: Diagnosis of Cardiac Arrhythmias Using Surface ECG and Other Non-invasive Means 7: Narrow-QRS Tachycardias: Differential Diagnosis at Bedside Introduction Initiation and Termination of SVT Regularity of Tachycardia Cycle Length P/QRS Relationship Vagal Maneuvers and Adenosine Diagnosis Use of Implantable Devices for SVT Diagnosis Esophageal Recording and Atrial Pacing References 8: Wide Complex Tachycardia Introduction Causes of Wide Complex Tachycardia Clinical Approach Electrocardiographic Approach QRS-Morphology-Based Algorithms Electrophysiology Study Approach (Table 8.1) References 9: Bradyarrhythmias Introduction Embryology and Basic Physiology of the Cardiac Conduction System Sinus Node Dysfunction Diagnostic Evaluation of Sinus Node Dysfunction AV Node Dysfunction (Table 9.2) Diagnostic Evaluation of AV Node Dysfunction Categorization of AV Block Other Causes of AV Block References 10: Pacemaker-Mediated Arrhythmias Introduction Repetitive Reentrant Ventriculoatrial Synchrony (RRVAS) Repetitive Non-reentrant Ventriculoatrial Synchrony (RNRVAS) Repetitive Non-reentrant Ventriculoatrial 1:2 Synchrony (RNRVA1:2S) References Part III: Diagnosis of Cardiac Arrhythmias: Intracardiac Approaches 11: Intracardiac Mapping in the Cardiac Electrophysiology Laboratory Essential Principles Types of Cardiac Mapping Activation Mapping Entrainment Mapping Pacemapping Voltage Mapping Mapping Based on Complex Fractionated Atrial Electrograms Focal Impulse and Rotor Modulation Mapping Types of Three-Dimensional Mapping Systems CARTO® EnSite™ NavX™ System Rhythmia HDx™ Image Integration in Mapping Techniques Future Directions References 12: Electrophysiological Maneuvers in Arrhythmia Analysis Introduction Maneuvers to Aid in the Diagnosis of Paroxysmal Supraventricular Tachycardia (PSVT) Pacing During Sinus Rhythm Ventricular Pacing During Sinus Rhythm Para-Hisian Pacing During Sinus Rhythm Atrial Pacing During Sinus Rhythm Key Observations After the Induction of Supraventricular Tachycardia Pacing Maneuvers During Supraventricular Tachycardia Single Extrastimuli Delivered During Supraventricular Tachycardia Atrial Extrastimuli During Supraventricular Tachycardia Ventricular Extrastimuli During Supraventricular Tachycardia Overdrive Pacing During Supraventricular Tachycardia Ventricular Overdrive Pacing Determining the Response to Ventricular Overdrive Pacing Analyzing the Response Immediately After Pacing Utilizing the Transition Zone to Differentiate PSVT Mechanisms Utilizing the Post-pacing Interval (PPI) and Tachycardia Cycle Length (TCL) Difference to Differentiate PSVT Mechanisms The Stimulus to Atrium (SA) – Ventricle to Atrium (VA) Difference Determining the Response to Atrial Overdrive Pacing VA Linking AOP to Rule Out Junctional Tachycardia Maneuvers in the Differentiation of Wide Complex Tachycardias Key Observations After the Induction of a Wide Complex Tachycardia Pacing Maneuvers During Wide Complex Tachycardia Single Extrastimuli Delivered During Wide Complex Tachycardia Overdrive Pacing During Wide Complex Tachycardia Maneuvers to Aid in the Localization of Ventricular Tachycardia Circuits Mapping During Sinus Rhythm Pace Mapping Focal Ventricular Tachycardia Pace Mapping Reentrant Ventricular Tachycardia Mapping During Ventricular Tachycardia Entrainment Mapping During Ventricular Tachycardia Presence of Manifest or Concealed Fusion Post-pacing Interval and Tachycardia Cycle Length Difference of the Entrained Drivetrain Measuring the Stimulus to QRS (S-QRS) and Electrogram to QRS (EGM-QRS) Conclusion References Part IV: Specific Arrhythmias 13: Atrio-ventricular Nodal Reentry Introduction Noninvasive Diagnosis of SVT AVNRT Mechanism Management of AVNRT Elecrophysiologic Testing and Tachycardia Ablation Summary References 14: Atrioventricular Reentry Tachycardia Introduction Clinical Features ECG Manifestation and Localization Baseline ECG P Wave During Tachycardia Rhythm Tracing Analysis Initiation During Tachycardia Termination Unusual Accessory Pathways Electrophysiologic Study Retrograde Atrial Activation Sequence Atrial Extrastimulus (AES) Atrial Overdrive Pacing (AOP) Ventricular Extrastimulus (VES) Initiation VA Relationship BBB During Tachycardia Diagnostic Maneuvers VA Interval (V Pacing SR) Differential RV Pacing Para-Hisian Pacing HA Interval (V Pacing During SR or Entrainment) His-Refractory Extrastimulation (V Pacing During Tachycardia) Transition Zone (VOP During Tachycardia Regardless of the Success of the Entrainment) Entrainment A(H)V Versus AA(H)V Response (VOP or Entrainment) PPI-TCL SA-VA Difference (VOP or Entrainment) Ventricular Fusion Differential Entrainment Antegrade His Capture Para-Hisian Entrainment AH interval (Atrial Pacing During SR) ∆VA Interval (VA Linking) Ablation of Accessory Pathway Access Mapping and Ablation Rare Types of SVT Permanent Junctional Reciprocating Tachycardia (PJRT) Atriofascicular (AF) Pathway Nodofascicular/Nodoventricular (NF/NV) Pathway Fasciculoventricular AP (FV) [89, 90] Subepicardial AP Summary References 15: Atrial Tachycardia Introduction Defining Atrial Tachycardia Focal Atrial Tachycardia and Microreentry Tachycardias Macroreentrant Atrial Tachycardias Sinus Node Reentrant Atrial Tachycardia Atrial Tachycardia After Previous Atrial Fibrillation Ablation Atrial Tachycardias After Previous Heart Surgery Electrocardiogram Characteristics of Atrial Tachycardias Electrophysiological Maneuvers to Differentiate AT from Supraventricular Tachycardias Mapping and Ablation of Atrial Tachycardias Success Rates of Catheter Ablation of Focal and Macroreentrant Atrial Tachycardias References 16: Pharmacologic Management of Atrial Fibrillation and Flutter Introduction Patterns of AF Paroxysmal AF Persistent AF Permanent AF Subclinical AF (SCAF) Goals of Treatment Rate Control Versus Rhythm Control Mortality Quality of Life and Exercise Tolerance Ventricular and Atrial Structure and Function Prevention of Thromboembolism Specific Drugs for Pharmacologic Cardioversion and for the Maintenance of Sinus Rhythm Specific Drugs for Maintenance of Sinus Rhythm Class Ia Quinidine Procainamide Disopyramide Class Ib Class Ic Propafenone and Flecainide Class II Class III Sotalol Dofetilide Dronedarone Amiodarone Class IV Specific Drugs for Conversion to Sinus Rhythm Ibutilide Vernakalant Drugs Used for Rhythm Control that Have Not Been Classically Considered as Antiarrhythmics Ranolazine Specific Drugs for the Control of Ventricular Rate in AF Class I Class II Class III Class IV Digoxin Drug Selection in Specific Populations Minimal Disease Coronary Disease Heart Failure LVH Anticoagulation Drugs for Anticoagulation of AF Patients Warfarin and ASA NOACs Dabigatran Apixaban Rivaroxaban Edoxaban Interactions Transitioning to and from Warfarin and DOACs Reversal Triple Therapy Atrial Flutter References 17: Atrial Fibrillation: Catheter Ablation and a Hybrid Approach Background Pulmonary Vein Isolation Ablation of Non-pulmonary Vein Triggers and Substrate Anticoagulation Colchicine and Other Anti-inflammatory Drugs Safety Outcome Studies Hybrid Approach Economic Impact References 18: Ventricular Tachycardia and Fibrillation: Pharmacologic Therapy Class IA Antiarrhythmic Drugs Lidocaine Mexiletine Flecainide Propafenone Beta-Blockers Amiodarone Sotalol Dofetilide Ibutilide Antiarrhythmic Drugs in Patients with ICDs Proper Selection of an Antiarrhythmic Drug for VT/VF Syndromes References 19: Ventricular Tachycardia: Catheter Ablation Introduction Definitions VT Mechanism Triggered Activity and Automaticity Scar-Related Reentry Reentry in the Purkinje System and Ventricular Fibrillation Indications for VT Ablation Patients with Structurally Normal Heart Patients with Ischemic Heart Disease Patients with Nonischemic Cardiomyopathy (NICM) Patients with Congenital Heart Disease and Inherited Arrhythmias Procedural Planning for VT Ablation Preprocedural Risk Assessment 12-Lead Electrocardiogram and Body Surface Mapping Before Ventricular Tachycardia Ablation Ventricular Tachycardia in the Absence of Structural Heart Disease Post-infarction Ventricular Tachycardia Ventricular Tachycardia in Nonischemic Cardiomyopathy Bundle Branch Reentrant Ventricular Tachycardia ICD Electrogram Information Epicardial Ventricular Tachycardia Mapping and Imaging Techniques Mapping Catheters Activation Mapping Entrainment Mapping Pace Mapping Sinus Rhythm Substrate Mapping End Points of Catheter Ablation of Ventricular Tachycardia References 20: Acquired Long QT Syndrome and Torsades de Pointes Introduction History of Acquired Long QT Syndrome with Particular Focus on Drug-Induced QT Prolongation Pathogenesis of Acquired Long QT Syndrome Secondary Factors as Triggers of Acquired Long QT Syndrome The Underlying Genetic Factor Treatments Future Plans to Elucidate Acquired Long QT Syndrome References 21: Indications for Implantable Cardioverter Defibrillators Introduction Overview of Implantable Cardioverter Defibrillator Indications Secondary Prevention Primary Prevention Inherited Cardiomyopathies and Channelopathies Hypertrophic Cardiomyopathy Arrhythmogenic Right Ventricular Cardiomyopathy Long QT Syndrome Short QT Syndrome Brugada Syndrome Catecholaminergic Polymorphic Ventricular Tachycardia Early Repolarization Syndrome Implantable Cardioverter Defibrillators in Congenital Heart Disease Implantable Cardioverter Defibrillators Implantation for Children Subcutaneous Implantable Cardioverter Defibrillators Conclusions and Future Directions References 22: Indications for Temporary and Permanent Pacemakers Introduction Temporary Pacemakers Temporary Pacing Modalities Transcutaneous Pacing Transesophageal Pacing Transvenous Temporary Pacing Bedside Transvenous Pacing Technique Externalized Semipermanent Pacing Epicardial Temporary Pacing Indications for Temporary Pacing Sinus Node Dysfunction Atrioventricular Block Cardiac Surgery Special Circumstances Permanent Pacemakers Pacing Modalities Indications for Permanent Pacemakers Sinus Node Dysfunction Atrioventricular Block Conduction Disorders with 1:1 Conduction Complications and Monitoring References 23: Overview of Syncope Definition Loss of Consciousness Rapid Onset Short Duration Spontaneous Recovery Due to Cerebral Hypoperfusion Epidemiology and Demographics Initial Evaluation General Considerations History History of the Present Episode Past Medical History Family History Physical Examination Ancillary Testing Echocardiogram Blood Testing Other Cardiac Imaging Electrocardiographic Monitoring Exercise Testing Tilt Table Testing [15, 16] Testing of Autonomic Function Carotid Sinus Massage Invasive Electrophysiology Testing Unnecessary Testing Risk Stratification Pathophysiology of Syncope Cerebral Perfusion Baroreflex System Cerebral Blood Flow Cerebral Autoregulation Classification of the Causes of Syncope Reflex Syncope Vasovagal Syncope Carotid Sinus Syndrome Situational Syncope Situational Syncope Related to the Respiratory Tract Situational Syncope Related to the GI Tract Situational Syncope Related to the Genitourinary Tract Syncope due to Orthostatic Hypotension Primary Autonomic Dysfunction Secondary Autonomic Dysfunction Syncope due to Cardiac Arrhythmia Bradyarrhythmias Tachyarrhythmias [57] Supraventricular Tachycardia VT Associated with Structural Heart Disease Idiopathic Ventricular Tachycardias Less Common Tachyarrhythmias, “Channelopathies” Syncope due to Structural Cardiac and Cardiopulmonary Causes Cerebrovascular Causes of Syncope Treatment of Syncope Treatment of Cardiac Syncope Syncope Secondary to Structural Heart Disease Syncope due to Cardiac Arrhythmia Treatment of Non-cardiac Syncope Syncope Caused by Orthostatic Hypotension [18] Syncope Caused by Reflex Syncope Treatment of Vasovagal Syncope Conclusions References Part V: Arrhythmias-Related Cardiomyopathy and Others 24: Arrhythmia-Induced Cardiomyopathies Introduction Causes Epidemiology Mechanisms Clinical Features Diagnosis Principles of Management Management of Different Arrhythmias in AIC Patients Atrial Fibrillation Atrial Flutter Frequent PVCs and VT Reentrant Supraventricular Tachycardia Sinus Tachycardia Arrhythmias More Common in Children Recovery of LVEF Recurrence of AIC Recovery of AIC: Reality or Misnomer? Conclusions References 25: Cardiac Resynchronization Therapy Introduction Physiology Behind Dyssynchrony Physiological Benefits of CRT CRT Major Landmark Trials Moderate to Severe Heart Failure Mild Heart Failure Considerations at the CRT Implant Major Society Guidelines for CRT Implantation Nonresponders CRT in Selected Population Atrial Fibrillation Right Bundle Branch Block Patients with Pacemakers Patients with Ejection Fraction Greater than 35% Conclusion His Bundle Pacing Introduction Deleterious Effects of RV Pacing Anatomy of His Bundle Implantation Technique Terminologies in HBP: Selective vs Nonselective His Bundle Pacing Role of His Bundle Pacing His Bundle Pacing in Heart Failure His Bundle Pacing in AV Block Left Bundle Pacing Pitfalls and Challenges in His Bundle Pacing The Future References 26: Anti-arrhythmic Effects of Non-anti-arrhythmic Drugs or Therapies Introduction Dihydropyridine Calcium Channel Blockers Potassium Channel Activator Nicorandil Antianginal Drug Ranolazine Angiotensin-Converting Enzyme Inhibitors and Angiotensin Receptor Blockers Potassium-Sparing Diuretics Anti-diabetic Medications HMG-CoA Reductase Inhibitors (Statins) Gout Medications: Colchicine and Allopurinol Non-steroidal Anti-inflammatory Drugs Corticosteroids Naturally Occurring Compounds (Omega-3 Fatty Acid) Traditional Chinese Medicines Conclusion References Part VI: Arrhythmias in Specific Populations 27: Arrhythmias in the Athlete Bradyarrhythmias Heart Block Supraventricular Tachycardias Atrioventricular Nodal Reentrant Tachycardia (AVNRT) Atrioventricular Reentrant Tachycardia (AVRT) Atrial Tachycardia Atrial Fibrillation and Flutter Pre-participation Screening Inherited Arrhythmia Syndromes Commotio Cordis Emergency Action Plans Evaluation of the Athlete Treatment Updated ICD Recommendations Conclusion References 28: Arrhythmias During Pregnancy and Postpartum Introduction Mechanism of Arrhythmia During Pregnancy Prevalence and Consequences of Arrhythmias During Pregnancy General Management Issues Diagnostic Testing During Pregnancy Antiarrhythmic Drugs Class IA Agents Class IB Agents Class IC Agents Class II Agents Class III Agents Class IV Agents Other Agents Electrical Cardioversion Catheter Ablation in Pregnancy The Management of Specific Arrhythmias During Pregnancy Tachyarrhythmias Sinus Tachycardia Atrial and Ventricular Ectopy Supraventricular Tachycardia Atrial Fibrillation and Flutter Ventricular Tachycardia and Sudden Cardiac Death Ventricular Tachycardia in Women with Structural Heart Disease Idiopathic Ventricular Tachycardia in Pregnant Women Long QT Syndrome Bradycardia and Conduction Disorders Cardiac Arrest Conclusion References 29: Arrhythmias in Children and Patients with Congenital Heart Disease Introduction Embryology and Congenital Abnormalities of the Specialized Conduction System Levotransposition of the Great Arteries Tricuspid Atresia Ebstein Anomaly of the Tricuspid Valve Atrioventricular Septal Defect Heterotaxy Arrhythmias Associated with Common Congenital Heart Defects Atrial Septal Defect Ventricular Septal Defect Pulmonic Stenosis Aortic Stenosis Arrhythmias in Children and Adults Following Congenital Heart Surgery Sinoatrial Node Dysfunction Atrial Tachycardias Ventricular Tachycardia and Sudden Death Postoperative AV Block Clinical Conditions and Arrhythmias of Specific Concern to Infants, Children, and Teenagers Fetal Arrhythmias Congenital Complete Heart Block Supraventricular Tachycardia (SVT) and Preexcitation Chaotic Atrial Tachycardia and Atrial Flutter Congenital Junctional Ectopic Tachycardia Postoperative Junctional Ectopic Tachycardia Arrhythmias and Conduction Abnormalities Presenting in Childhood and Associated with Neuromuscular, Mitochondrial, Metabolic, Oncogene, and Transcription Factor Abnormalities Therapies for Pediatric Arrhythmias Pharmacologic Therapies Catheter Ablation Pacemakers in Children and in Congenital Heart Disease Implantable Cardioverter/Defibrillators References Part VII: Inherited Cardiac Arrhythmia Syndromes 30: J Wave Syndromes: Brugada and Early Repolarization Syndromes Introduction Prevalence of JWS and Arrhythmic SCD Risk Assessment Diagnostic Criteria Pharmacological Tests Differential Diagnosis and Modulating Factors Similarities and Difference Between BrS and ERS Genetics Ionic and Cellular Mechanisms Underlying the JWS Therapy of JWS Implantable Cardioverter Defibrillator Pacemaker Therapy Radiofrequency Ablation (RFA) Therapy Pharmacologic Therapy References 31: Catecholaminergic Polymorphic Ventricular Tachycardia Introduction Etiology Clinical Presentation Clinical Diagnosis Differential Diagnosis Molecular Diagnostics DNA Testing CPVT Genes CPVT Phenocopies Therapy β-Blockers Calcium Channel Blockers Sodium Channel Blockers Left Cardiac Sympathetic Denervation Lifestyle Risk Stratification Implantable Cardioverter-Defibrillator Indications Recommendations During Pregnancy and Delivery Family Screening References 32: Arrhythmogenic Right Ventricular Cardiomyopathy Introduction Pathogenesis Histopathological Features Molecular Genetic Features and Pathogenesis Clinical Presentation and Natural History Epidemiology Phenotypic Expression Differential Diagnosis Prognosis Clinical Diagnosis Prognosis and Treatment Risk Stratification Therapy Lifestyle Changes Drug Therapy Catheter Ablation ICD Therapy Heart Transplant References 33: Congenital Long-QT Syndrome: From Genetics to Clinical Management Introduction Electrophysiological and Genetic Underpinnings of LQTS Clinical Presentation Type 1 LQTS (LQT1) Type 2 LQTS (LQT2) Type 3 LQTS (LQT3) Diagnosis Electrocardiography Exercise and Epinephrine Stress Testing Genetic Testing Risk Stratification and Clinical Management Risk Stratification General Precautions Pharmacologic Management Left Cardiac Sympathetic Denervation (LCSD) Device-Related Therapies Genotype-Guided Management Prevention Conclusions References 34: Short QT Syndrome Introduction Definition Clinical Manifestation Diagnosis Genetics Cellular Basis of Arrhythmogenesis in SQTS Approach to Therapy of Patients with SQTS Device Therapy (ICD) Pharmacologic Therapy RF Ablation Conclusion References Index