Pacemaker, ArtificialBiological ClocksSinoatrial NodeSick Sinus SyndromeHeart BlockEquipment FailureAtrioventricular BlockBradycardiaHyperpolarization-Activated Cyclic Nucleotide-Gated ChannelsCircadian RhythmElectrodes, ImplantedInterstitial Cells of CajalSuprachiasmatic NucleusDevice RemovalArrhythmias, CardiacEquipment SafetyElectrocardiographyHeart Conduction SystemCyclic Nucleotide-Gated Cation ChannelsPeriodicityAction PotentialsEquipment DesignAtrioventricular NodeElectrophysiologyDefibrillators, ImplantableFlufenamic AcidArrhythmia, SinusPeriod Circadian ProteinsTime FactorsSyncopeMembrane PotentialsHeart AtriaAtrial FunctionHeart RateTreatment OutcomeAtrial FibrillationTachycardiaProsthesis ImplantationForeign-Body MigrationIon ChannelsElectric Power SuppliesRespiratory CenterPotassium ChannelsElectromagnetic PhenomenaNeuronsFollow-Up StudiesSinoatrial BlockPatch-Clamp TechniquesProspective StudiesElectromagnetic FieldsHeartSubclavian VeinPurkinje FibersHeart InjuriesGastrointestinal MotilityEquipment Failure AnalysisTelemetryElectrocardiography, AmbulatoryHeart VentriclesDogsProsthesis-Related InfectionsCalciumCesiumTricuspid Valve StenosisSyncope, VasovagalPhotoperiodTetrodotoxinBundle-Branch BlockFinancial AuditRabbitsPotassiumElectric StimulationMortuary PracticeRetrospective StudiesBundle of HisEquipment ReuseElectrophysiologic Techniques, CardiacFloxacillinElectric ConductivityElectric FishEndocarditisSensitivity and SpecificityPeristalsisHousehold ArticlesCardiac ElectrophysiologyCLOCK ProteinsCircadian ClocksHeart Valve Prosthesis ImplantationMyenteric PlexusThapsiaTachycardia, Ectopic AtrialOscillometryElectric CountershockPylorusCatheter AblationIntestine, SmallAnti-Arrhythmia AgentsPyloric AntrumPalinuridaeMuscle, Smooth