MicroelectrodesDefibrillators, ImplantableImplantable NeurostimulatorsEquipment FailureTachycardia, VentricularElectrodes, ImplantedIon-Selective ElectrodesElectric CountershockProstheses and ImplantsVentricular FibrillationDeath, Sudden, CardiacPacemaker, ArtificialInfusion Pumps, ImplantableEquipment DesignArrhythmias, CardiacEquipment Failure AnalysisElectric InjuriesEquipment SafetyDevice RemovalSyncopeMembrane PotentialsAnti-Arrhythmia AgentsElectrochemistryTelemetryElectrophysiologyCardiac Pacing, ArtificialElectrocardiographyAction PotentialsMiniaturizationPotassiumAmiodaroneProsthesis ImplantationElectric Power SuppliesElectrodesFluorocarbon PolymersExtracellular SpaceNeural ProsthesesCardiac Resynchronization Therapy DevicesRadio Frequency Identification DeviceAmplifiers, ElectronicBiosensing TechniquesMicrochip Analytical ProceduresElectrocardiography, AmbulatoryElectric StimulationElectrochemical TechniquesHeart-Assist DevicesHeart FailureFollow-Up StudiesTreatment OutcomeHydrogen-Ion ConcentrationTime FactorsSodiumMonitoring, AmbulatoryElectrophysiologic Techniques, CardiacElectromagnetic PhenomenaBicarbonatesCardiac Resynchronization TherapyElectroplatingHeart ArrestPrimary PreventionElectric ImpedanceCatheters, IndwellingChloridesStrophanthidinTachycardiaHelix (Snails)NecturusMicromanipulationNecturus maculosusHeart Conduction SystemPurkinje FibersConductometryRemote Sensing TechnologyProsthesis-Related InfectionsWireless TechnologyNeuronsMicrotechnologyGlassDielectric SpectroscopyRetrospective StudiesStroke VolumeGuinea PigsIntracellular FluidProspective StudiesVentricular Dysfunction, LeftTachycardia, SupraventricularMicro-Electrical-Mechanical SystemsOxygenLeechesCardiomyopathiesDeath, SuddenElectric ConductivityBrugada SyndromeCarbonRisk AssessmentMonitoring, PhysiologicDiamondPotentiometryCardiomyopathy, DilatedIon Transport