Heart Defects, CongenitalHypertrophyCardiomegalyDefibrillators, ImplantableHypertrophy, Left VentricularMyocytes, CardiacMyocardiumHeartHypertrophy, Right VentricularArrhythmias, CardiacDeath, Sudden, CardiacVentricular RemodelingHeart FailureHeart VentriclesFibrosisEchocardiographyOrgan SizeAtrial Natriuretic FactorTachycardia, VentricularImplantable NeurostimulatorsBlood PressureCardiomyopathy, HypertrophicEquipment FailureMyocardial ContractionCalcineurinElectrocardiographyHypertensionDisease Models, AnimalAngiotensin IIElectric CountershockRats, Sprague-DawleyVentricular FibrillationMice, TransgenicInfusion Pumps, ImplantablePacemaker, ArtificialEndomyocardial FibrosisCardiomyopathiesCardiac OutputTime FactorsProstheses and ImplantsCell SizeSignal TransductionHemodynamicsCell EnlargementVentricular Function, LeftMyosin Heavy ChainsCardiac Pacing, ArtificialCells, CulturedRats, Inbred SHRIsoproterenolMice, KnockoutRats, WistarHeart DiseasesCardiomegaly, Exercise-InducedVentricular Dysfunction, LeftCardiomyopathy, DilatedVentricular PressureMice, Inbred C57BLHeart RatePhenylephrineElectrodes, ImplantedAnimals, NewbornRNA, MessengerMuscle ProteinsCardiac Surgical ProceduresConstrictionRats, Inbred WKYEquipment DesignTelemetryStroke VolumeSyncopeCardiotonic AgentsVentricular Function, RightElectric InjuriesTreatment OutcomeNFATC Transcription FactorsBody WeightAnti-Arrhythmia AgentsDevice RemovalGene Expression RegulationEquipment SafetyEndothelin-1Heart ArrestFollow-Up StudiesGATA4 Transcription FactorVentricular Dysfunction, RightVentricular MyosinsCardiac MyosinsNatriuretic Peptide, BrainSarcoplasmic Reticulum Calcium-Transporting ATPasesCardiac Output, LowGene ExpressionAntihypertensive AgentsPhysical Conditioning, AnimalMyocardial InfarctionAortaReceptors, Adrenergic, betaMuscle CellsReceptor, Angiotensin, Type 1Diastole