Papillary MusclesMusclesNecrosisMyocardial ContractionTumor Necrosis Factor-alphaMuscle ProteinsChordae TendineaeMuscle, SmoothMuscle, SkeletalMuscle ContractionMuscle Fibers, SkeletalMuscle, Smooth, VascularMitral Valve InsufficiencyGuinea PigsMuscle DevelopmentMitral ValveHeartFerretsMyocardiumAction PotentialsHeart VentriclesMuscle FatigueMuscle Fibers, Fast-TwitchMuscle DenervationIsometric ContractionMuscle Fibers, Slow-TwitchAequorinHeart Rupture, Post-InfarctionCalciumRabbitsMyocytes, Smooth MuscleMuscle RelaxationMitochondria, MuscleTime FactorsElectric StimulationCineradiographyReceptors, Tumor Necrosis FactorHeart RuptureNeck MusclesOculomotor MusclesMuscle, StriatedDepression, ChemicalCatsMuscle SpindlesDogsPurkinje FibersIsoproterenolRespiratory MusclesMuscle WeaknessVentricular FunctionMyofibrilsRats, WistarMembrane PotentialsMitral Valve AnnuloplastyCells, CulturedEndocardiumAbdominal MusclesMuscle CellsQuadriceps MuscleDose-Response Relationship, DrugElectrophysiologyCardiomyopathiesBiomechanical PhenomenaCross CirculationMasseter MuscleStimulation, ChemicalAnti-Arrhythmia AgentsFacial MusclesMasticatory MusclesIntercostal MusclesElectromyographyOuabainMuscular AtrophyHeart Conduction SystemRats, Sprague-DawleyMicroelectrodesEchocardiographySatellite Cells, Skeletal MuscleRyanodineSarcolemmaSarcoplasmic ReticulumRupture, SpontaneousReceptors, Tumor Necrosis Factor, Type IIRNA, MessengerCardiotonic AgentsAdrenergic beta-AgonistsCarnivoraPectoralis MusclesMuscular DiseasesRefractory Period, ElectrophysiologicalMyosin Heavy ChainsEchocardiography, Three-DimensionalPerfusionMitral Valve ProlapseDigitoxinQuinidinePotassiumEchocardiography, TransesophagealHeart Valve Prosthesis ImplantationSuture Techniques