Heart BlockPacemaker, ArtificialHeartAdams-Stokes SyndromeHeart RateAtrioventricular BlockBradycardiaAtrioventricular NodeSinoatrial NodeElectrocardiographySick Sinus SyndromeBiological ClocksHeart Conduction SystemRNA, Small CytoplasmicHeart Defects, CongenitalAntibodies, AntinuclearFetal HeartFetal DiseasesBundle of HisHeart FailureBundle-Branch BlockCardiac Pacing, ArtificialHeart DiseasesHeart Rate, FetalHeart AtriaSyncopeArrhythmias, CardiacEquipment FailureMaternal-Fetal ExchangeRibonucleoproteinsNerve BlockSteroids, FluorinatedMyocardiumEchocardiographyHeart SeptumKearns-Sayre SyndromeHeart TransplantationEndocardial FibroelastosisArrhythmia, SinusHeart Septal Defects, VentricularCardiomyopathiesTime FactorsHyperpolarization-Activated Cyclic Nucleotide-Gated ChannelsPregnancyElectrocardiography, AmbulatoryLupus Erythematosus, CutaneousMagnetocardiographyAutoantigensInfant, NewbornFollow-Up StudiesAutoantibodiesMyocytes, CardiacCircadian RhythmTreatment OutcomeCardiac CatheterizationHeart ValvesHydrops FetalisLupus Erythematosus, SystemicDogsElectrodes, ImplantedPregnancy ComplicationsHeart Valve ProsthesisCatheter AblationCardiomyopathy, DilatedInterstitial Cells of CajalHemodynamicsMyocardial InfarctionAutoimmune DiseasesAction PotentialsSuprachiasmatic NucleusElectrophysiologyTransposition of Great VesselsCardiomyopathy, HypertrophicProspective StudiesUltrasonography, PrenatalDevice RemovalElectrophysiologic Techniques, CardiacImmunity, Maternally-AcquiredCollagen DiseasesMyocarditisBetamethasoneRetrospective StudiesEquipment SafetyCardiac Surgical ProceduresPrenatal DiagnosisHeart Valve Prosthesis ImplantationHeart AuscultationCyclic Nucleotide-Gated Cation Channels