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Syncope

Definitions and Scope Definitions Syncope is transient loss of consciousness caused by a temporary reduction in cerebral perfusion. , This definition excludes trauma, seizure, metabolic derangements, and psychiatric conditions, which cause loss of consciousness by different mechanisms. , In true syncope, changes in cardiac output, vascular tone, cardiac rhythm, or a combination of these factors reduce cerebral perfusion, triggering reflexive loss of both consciousness and control…

Drug-Induced Ventricular Arrhythmias

Acknowledgments This work is supported in part by grants from the US Public Health Service (HL133127, HL108037, and HL081707) and the American Heart Association (18SFRN34230125). Introduction A major challenge in prescribing antiarrhythmic drugs is the occurrence of drug-induced ventricular arrhythmias that can lead to syncope and sudden cardiac death. In recent years, an increasing number of cardiac and noncardiac drugs have been identified that cause proarrhythmia,…

Mapping and Ablation of Ventricular Fibrillation

Acknowledgments This work was supported by the National Research Agency (ANR-10-IAHU-04) and the Leducq Foundation (RHYTHM Network). F.D.R. is supported by a Canadian Institutes of Health Research Banting Postdoctoral Fellowship and a Royal College of Physicians and Surgeons of Canada Detweiler Travelling Fellowship. Background Sudden cardiac death (SCD; see Chapter 79 ) remains an important health problem globally, with nearly 350,000 victims per year in the…

Idiopathic and Short-Coupled Ventricular Fibrillation

The definition of the clinical syndrome of idiopathic ventricular fibrillation (IVF) has evolved over time and continues to do so. Historically, the term IVF was used to describe polymorphic ventricular tachycardia (VT)/ventricular fibrillation (VF) in the absence of ischemia, structural heart disease (SHD), or reversible metabolic-toxicologic conditions. As our ability to characterize, diagnose, and manage inherited arrhythmia syndromes has improved both clinically and genetically, the proportion…

J Wave Syndromes

The term J wave syndromes denotes a clinical spectrum of diseases that differ from each other in etiology and clinical characteristics, yet they have similar electrocardiographic features and appear to share arrhythmogenic mechanisms. They include disorders caused by genetic mutations (Brugada syndrome), acquired disorders (myocardial ischemia and hypothermia), and diseases of unclear etiology (idiopathic ventricular fibrillation [VF] with early repolarization) ( Table 99.1 ). The proposed…

Timothy Syndrome

Introduction Long QT syndrome (LQTS) is an arrhythmogenic disorder that presents with QT interval prolongation and high risk for onset of ventricular arrhythmias and sudden death. It is a genetically heterogeneous condition involving at least 17 different genetic loci. , The focus of this chapter is the locus on chromosome 12p13.33 encompassing the CACNA1c gene that is the cause of Timothy syndrome (TS), also defined as…

Andersen-Tawil Syndrome

Introduction Andersen-Tawil syndrome (ATS) is a clinically pleiotropic disorder resulting from mutations in an ion channel gene that modulates the most terminal portion of cardiac repolarization. ATS is fundamentally a disorder of ventricular repolarization. Although initially classified as long QT syndrome (LQTS) type 7, the noncardiac and cardiac clinical manifestations are distinct from classic LQTS and include dysmorphic features, periodic paralysis, and a high burden of…

Long and Short QT Syndromes

Long QT Syndrome Congenital long QT syndrome (LQTS), a leading cause of sudden death in the young, is characterized by a prolongation of the QT interval in the standard electrocardiogram (ECG) and by syncopal episodes, which often result in cardiac arrest (CA) and sudden death and usually occur under physical or emotional stress in otherwise healthy young individuals. The availability of very effective therapies for this…

Brugada Syndrome

In 1992, a manuscript titled “Right bundle branch block, persistent ST segment elevation and sudden cardiac death: a distinct clinical and electrocardiographical syndrome” was published in the Journal of the American College of Cardiology. This publication described eight individuals with a common phenotype: all had a structurally normal heart and had been resuscitated from sudden cardiac death (SCD) caused by documented ventricular fibrillation (VF). All of…

Mitral Valve Prolapse, Ventricular Arrhythmias, and Sudden Death

Introduction Malignant mitral valve prolapse (MVP) syndrome has been recently described in a subset of patients who may be at greater risk for sudden cardiac death (SCD), made up of young women with mostly bileaflet MVP, midsystolic click, biphasic or inverted T waves in the inferior leads, and polymorphic/right bundle branch block (RBBB) morphology complex ventricular arrhythmias, in the absence of significant regurgitation. Subsequent clinic-pathologic data,…

Ventricular Arrhythmias in Takotsubo Cardiomyopathy

Takotsubo cardiomyopathy (TC), also known as apical ballooning syndrome or stress cardiomyopathy, is a reversible cause of left ventricular (LV) dysfunction that is frequently precipitated by an emotionally or physically stressful event. Dote and colleagues first reported the occurrence of an unusual systolic LV configuration in patients suspected of acute myocardial infarction (MI). They coined the term “takotsubo cardiomyopathy” because of the resemblance of the LV…

Arrhythmias and Conduction Disturbances in Noncompaction Cardiomyopathy

Acknowledgments J.A.T. was funded, in part, by the National Institutes of Health (NIH), National Heart Lung, and Blood Institute (NHLBI) with grants RO1 HL53392 and RO1 HL087000, for the Pediatric Cardiomyopathy Registry and Pediatric Cardiomyopathy Specimen Repository, RO1 HL151438, and the St. Jude Chair of Excellence in Pediatric Cardiology and Cardiac Research. — This chapter discusses the form of cardiomyopathy known as left ventricular noncompaction cardiomyopathy…

Catecholaminergic Polymorphic Ventricular Tachycardia

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited arrhythmia syndrome that is characterized by exercise or emotional stress–induced bidirectional or polymorphic ventricular tachyarrhythmias in patients with a normal electrocardiogram (ECG) at rest and in the absence of structural heart disease. Its prevalence in the general population is unknown but is estimated to be approximately 1 in 10,000. CPVT is a significant cause of sudden cardiac arrest…

Ventricular Tachycardias in Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is an inherited cardiomyopathy that is characterized by ventricular arrhythmias, an increased risk for sudden cardiac death (SCD), and abnormalities of right ventricular (RV) structure and function. Although structural involvement of the RV predominates, it is now recognized that involvement of the left ventricle (LV) is not uncommon. In most patients in the United States, structural abnormalities of the RV predominate…

Ventricular Tachyarrhythmias in Hypertrophic Cardiomyopathy: Sudden Death, Risk Stratification, and Prevention With Implantable Defibrillators

Hypertrophic cardiomyopathy (HCM) is a common genetic cardiac disease with global distribution and heterogeneous morphologic expression and natural history. , In the current cardiovascular treatment era, HCM is associated with very low disease-related mortality with an expectation for normal longevity and excellent quality of life for the majority of patients ( Fig. 89.1 ). , Nevertheless, sudden cardiac death (SCD) remains the most visible and devastating…

Lamin A/C, Noncompaction, and Other Genetic Cardiomyopathies With Ventricular Arrhythmias

Introduction The study of inherited cardiomyopathies is a rapidly evolving area of cardiology. Increasingly recognized because of improvements in cardiac imaging, clinical genetics, and clinical knowledge, these unique disease entities often present in healthy individuals with dramatic clinical implications, both for the affected individual and their relatives. With an increased risk for associated ventricular arrhythmias (VAs), a clinical priority focuses on risk stratification and prevention of…

Ventricular Tachycardia in Patients With Dilated Cardiomyopathy

Definition, Epidemiology, and Etiology of Dilated Cardiomyopathy Definition Dilated cardiomyopathy (DCM) is a primary disease of the heart muscle that is characterized by dilation of the heart chambers and decreased heart contractility. Two echocardiographic criteria were proposed to define DCM: left ventricular (LV) fractional shortening less than 25% or LV ejection fraction (EF) less than 45%, and LV end-diastolic diameter larger than 117% of the predicted…

Ablation of Postmyocardial Infarction Ventricular Tachycardia

Historical Perspective In patients with a history of myocardial infarction (MI) who experience episodes of sustained ventricular tachycardia (VT), surgical treatment was the mainstay of procedural therapy before the advent of catheter ablation. Initial experience with aneurysmectomy showed only moderate success rates for long-term arrhythmia control. Further refinement of surgical technique with the removal of subendocardial tissue surrounding the aneurysm increased success rates even further, emphasizing…

Ischemic Heart Disease

Acknowledgments We thank David Soto, PhD, for his assistance with the preparation of figures. Electroanatomic Substrate If not promptly revascularized, coronary artery occlusion leads to infarction with subsequent scarring of the ventricular myocardium. During the infarct healing process, necrotic myocardium is replaced by fibrous tissue that surrounds surviving myocytes. These bundles of surviving, diseased myocytes are the key substrate for reentrant, monomorphic ventricular tachycardia (VT). With…

Bundle Branch Reentry Tachycardia

Bundle branch reentry ventricular tachycardia (BBRVT), first elucidated by Guerot and colleagues in 1974, is a unique, usually fast (200–300 beats/min), monomorphic tachycardia associated with hemodynamic collapse, syncope, and/or cardiac arrest. It has also been described as a mechanism for nonsustained VT and coupled ventricular ectopy. , BBRVT is caused by a macroreentrant circuit involving the right and left bundle branches, an upper common pathway, and…