ElectrocardiographyArrhythmias, CardiacMyocytes, CardiacHeartUltrasonographyCardiac OutputHeart RateUltrasonicsDeath, Sudden, CardiacUltrasonic TherapyHeart Conduction SystemHeart DiseasesMyocardial InfarctionHigh-Intensity Focused Ultrasound AblationUltrasonography, InterventionalVectorcardiographyEchocardiographyProspective StudiesCardiac Surgical ProceduresSignal Processing, Computer-AssistedPredictive Value of TestsHeart VentriclesTime FactorsSensitivity and SpecificityMicrobubblesElectrocardiography, AmbulatoryCardiac Pacing, ArtificialBrugada SyndromeUltrasonography, PrenatalCardiac CatheterizationTransducersMyocardiumCardiomegalyLong QT SyndromeReproducibility of ResultsBundle-Branch BlockFollow-Up StudiesCardiomyopathiesTreatment OutcomeMyocardial ContractionMyocardial IschemiaChest PainTachycardiaVentricular FibrillationBlood PressureRetrospective StudiesCoronary DiseaseTachycardia, VentricularCoronary AngiographyRisk FactorsExercise TestHeart FailureHeart BlockHeart ArrestHemodynamicsSyncopeCardiac TamponadeCardiac Complexes, PrematurePregnancyVentricular Function, LeftTelemetryPhonocardiographyUltrasonography, DopplerAnti-Arrhythmia AgentsContrast MediaDiagnosis, Computer-AssistedCoronary VesselsBody Surface Potential MappingAutonomic Nervous SystemStroke VolumeMonitoring, PhysiologicModels, CardiovascularHeart AtriaAtrial FibrillationVentricular Dysfunction, LeftVentricular Premature ComplexesUltrasonography, Doppler, ColorDogsImaging, Three-DimensionalPrognosisCreatine KinaseBradycardiaHeart Defects, CongenitalCardiac VolumeArrhythmia, SinusRisk AssessmentHypertrophy, Left VentricularEquipment DesignElectrophysiologic Techniques, CardiacCardiomyopathy, HypertrophicAngina PectorisCardiomyopathy, DilatedTroponin IVentricular FunctionHeart Function TestsPericarditisDeath, SuddenMicroscopy, AcousticPacemaker, ArtificialCardiac Resynchronization Therapy