Papillary MusclesHeart RuptureHeart Rupture, Post-InfarctionRupture, SpontaneousMitral Valve InsufficiencyRadionuclide VentriculographyRuptureEchocardiography, TransesophagealHeart Valve Prosthesis ImplantationCardiomyopathiesPectoralis MusclesMusclesCoronary AngiographyMyocardial ContractionSplenic RuptureChordae TendineaeAortic RuptureMuscle ProteinsMuscle, SmoothMuscle, SkeletalMuscle ContractionMuscle Fibers, SkeletalMuscle, Smooth, VascularUterine RuptureGuinea PigsMitral ValveMuscle DevelopmentHeartFerretsFetal Membranes, Premature RuptureHeart VentriclesMyocardial InfarctionAction PotentialsMyocardiumElectrocardiographyMuscle FatigueMuscle Fibers, Fast-TwitchMuscle DenervationIsometric ContractionMuscle Fibers, Slow-TwitchAequorinMyocytes, Smooth MuscleCalciumRabbitsMuscle RelaxationMitochondria, MuscleTime FactorsElectric StimulationRetrospective StudiesCineradiographyNeck MusclesOculomotor MusclesMuscle, StriatedDepression, ChemicalMuscle SpindlesCatsPurkinje FibersRespiratory MusclesBiomechanical PhenomenaDogsAneurysm, RupturedIsoproterenolMuscle WeaknessVentricular FunctionMyofibrilsQuadriceps MuscleMembrane PotentialsMitral Valve Annuloplasty