Arrhythmias, CardiacHeartCircadian RhythmHeart RateDefibrillators, ImplantableAtrial FibrillationElectrocardiographyAnti-Arrhythmia AgentsPacemaker, ArtificialEuropeElectrocardiography, AmbulatoryCranial SinusesArrhythmia, SinusMaxillary SinusHeart Conduction SystemCardiac Pacing, ArtificialCatheter AblationParanasal SinusesCardiologyTachycardia, VentricularSinus of ValsalvaElectric CountershockCavernous SinusSocieties, MedicalFractalsCarotid SinusCardiac Imaging TechniquesFrontal SinusParanasal Sinus DiseasesSphenoid SinusCoronary SinusHeart FailureDeath, Sudden, CardiacDevice RemovalSignal Processing, Computer-AssistedHeart AtriaSick Sinus SyndromeHeart DiseasesSinus Thrombosis, IntracranialTreatment OutcomeVentricular FibrillationEthmoid SinusHeart Defects, CongenitalHeart BlockTachycardia, SinusCardiac Resynchronization TherapyVentricular Premature ComplexesHealth Care SurveysHeart TransplantationTachycardiaCardiac Complexes, PrematureParanasal Sinus NeoplasmsMyocardiumTime FactorsSinoatrial NodeAtrial FlutterTachycardia, SupraventricularRisk FactorsDogsFetal HeartPractice Guidelines as TopicBiological ClocksLong QT SyndromeElectrophysiologic Techniques, CardiacMyocytes, CardiacMyocardial IschemiaPeriodicityMaxillary Sinus NeoplasmsPhysician's Practice PatternsAction PotentialsMyocardial ContractionBradycardiaHeart ValvesHeart VentriclesSuprachiasmatic NucleusFollow-Up StudiesAtrioventricular NodePilonidal SinusAmiodaroneModels, CardiovascularMyocardial InfarctionTransverse SinusesEchocardiographyFlecainidePeriod Circadian ProteinsHemodynamicsVentricular DysfunctionMyocardial Reperfusion InjuryHeart ArrestSyncopeSuperior Sagittal SinusAutonomic Nervous SystemCircadian Rhythm Signaling Peptides and ProteinsCardiomyopathiesHeart Function TestsProspective StudiesCardiomyopathy, DilatedBody Surface Potential MappingAdrenergic beta-AntagonistsActivity Cycles