Defibrillators, ImplantableDefibrillatorsHeartElectric CountershockVentricular FibrillationDeath, Sudden, CardiacTachycardia, VentricularArrhythmias, CardiacHeart RateHeart ArrestHeart FailureEquipment FailureMyocytes, CardiacCardiac Pacing, ArtificialPacemaker, ArtificialHeart DiseasesCardiac Resynchronization TherapyCardiopulmonary ResuscitationElectrocardiographyElectric InjuriesAnti-Arrhythmia AgentsEquipment SafetyHeart TransplantationCardiac OutputOut-of-Hospital Cardiac ArrestTreatment OutcomeHeart Defects, CongenitalAmiodaroneCardiomyopathiesDevice RemovalVentricular Dysfunction, LeftStroke VolumeFollow-Up StudiesTime FactorsCardiac Surgical ProceduresEquipment DesignMyocardiumElectrodes, ImplantedEquipment Failure AnalysisProspective StudiesCardiomyopathy, DilatedFetal HeartCardiac Resynchronization Therapy DevicesTachycardiaMyocardial IschemiaMyocardial InfarctionHeart AtriaMyocardial ContractionCardiac ElectrophysiologyCardiomegalyProsthesis ImplantationSyncopeRisk FactorsVentricular Function, LeftEmergency Medical ServicesEchocardiographyHeart Function TestsElectrophysiologic Techniques, CardiacRisk AssessmentHeart VentriclesHeart BlockRetrospective StudiesCardiac Output, LowHeart ValvesVolunteersCardiography, ImpedanceCardiac CatheterizationElectrocardiography, AmbulatoryAtrial FibrillationAdrenergic beta-AntagonistsBrugada SyndromeSurvival RateSurvival AnalysisDeath, SuddenHeart InjuriesHemodynamicsVentricular RemodelingResuscitationCardiac TamponadeVentricular DysfunctionHeart Conduction SystemTachycardia, SupraventricularCardiomyopathy, HypertrophicFirst AidEmergency TreatmentPredictive Value of TestsKaplan-Meier EstimateCoronary DiseaseModels, CardiovascularBurns, ElectricEndocardiumArrhythmogenic Right Ventricular DysplasiaHeart MassageAircraftProportional Hazards ModelsCardiotonic AgentsCardiac MyosinsTherapy, Computer-AssistedPrognosisIncidence