Bundle-Branch Block: A form of heart block in which the electrical stimulation of HEART VENTRICLES is interrupted at either one of the branches of BUNDLE OF HIS thus preventing the simultaneous depolarization of the two ventricles.Medial Forebrain Bundle: A complex group of fibers arising from the basal olfactory regions, the periamygdaloid region, and the septal nuclei, and passing to the lateral hypothalamus. Some fibers continue into the tegmentum.Patient Care Bundles: Small sets of evidence-based interventions for a defined patient population and care setting.Plant Vascular Bundle: A strand of primary conductive plant tissue consisting essentially of XYLEM, PHLOEM, and CAMBIUM.Hair Cells, Auditory: Sensory cells in the organ of Corti, characterized by their apical stereocilia (hair-like projections). The inner and outer hair cells, as defined by their proximity to the core of spongy bone (the modiolus), change morphologically along the COCHLEA. Towards the cochlear apex, the length of hair cell bodies and their apical STEREOCILIA increase, allowing differential responses to various frequencies of sound.Actins: Filamentous proteins that are the main constituent of the thin filaments of muscle fibers. The filaments (known also as filamentous or F-actin) can be dissociated into their globular subunits; each subunit is composed of a single polypeptide 375 amino acids long. This is known as globular or G-actin. In conjunction with MYOSINS, actin is responsible for the contraction and relaxation of muscle.Actin Cytoskeleton: Fibers composed of MICROFILAMENT PROTEINS, which are predominately ACTIN. They are the smallest of the cytoskeletal filaments.Microscopy, Electron: Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.Stereocilia: Mechanosensing organelles of hair cells which respond to fluid motion or fluid pressure changes. They have various functions in many different animals, but are primarily used in hearing.Hair Cells, Vestibular: Sensory cells in the acoustic maculae with their apical STEREOCILIA embedded in a gelatinous OTOLITHIC MEMBRANE. These hair cells are stimulated by the movement of otolithic membrane, and impulses are transmitted via the VESTIBULAR NERVE to the BRAIN STEM. Hair cells in the saccule and those in the utricle sense linear acceleration in vertical and horizontal directions, respectively.Heart Conduction System: An impulse-conducting system composed of modified cardiac muscle, having the power of spontaneous rhythmicity and conduction more highly developed than the rest of the heart.Protein Structure, Secondary: The level of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to alpha helices, beta strands (which align to form beta sheets) or other types of coils. This is the first folding level of protein conformation.Microfilament Proteins: Monomeric subunits of primarily globular ACTIN and found in the cytoplasmic matrix of almost all cells. They are often associated with microtubules and may play a role in cytoskeletal function and/or mediate movement of the cell or the organelles within the cell.Cytoskeleton: The network of filaments, tubules, and interconnecting filamentous bridges which give shape, structure, and organization to the cytoplasm.Models, Molecular: Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.Microtubules: Slender, cylindrical filaments found in the cytoskeleton of plant and animal cells. They are composed of the protein TUBULIN and are influenced by TUBULIN MODULATORS.Electrocardiography: Recording of the moment-to-moment electromotive forces of the HEART as projected onto various sites on the body's surface, delineated as a scalar function of time. The recording is monitored by a tracing on slow moving chart paper or by observing it on a cardioscope, which is a CATHODE RAY TUBE DISPLAY.Rana catesbeiana: A species of the family Ranidae (true frogs). The only anuran properly referred to by the common name "bullfrog", it is the largest native anuran in North America.Hair Cells, Auditory, Inner: Auditory sensory cells of organ of Corti, usually placed in one row medially to the core of spongy bone (the modiolus). Inner hair cells are in fewer numbers than the OUTER AUDITORY HAIR CELLS, and their STEREOCILIA are approximately twice as thick as those of the outer hair cells.Atrioventricular Node: A small nodular mass of specialized muscle fibers located in the interatrial septum near the opening of the coronary sinus. It gives rise to the atrioventricular bundle of the conduction system of the heart.Acoustic Maculae: The sensory areas on the vertical wall of the saccule and in the floor of the utricle. The hair cells in the maculae are innervated by fibers of the VESTIBULAR NERVE.Microscopy, Electron, Scanning: Microscopy in which the object is examined directly by an electron beam scanning the specimen point-by-point. The image is constructed by detecting the products of specimen interactions that are projected above the plane of the sample, such as backscattered electrons. Although SCANNING TRANSMISSION ELECTRON MICROSCOPY also scans the specimen point by point with the electron beam, the image is constructed by detecting the electrons, or their interaction products that are transmitted through the sample plane, so that is a form of TRANSMISSION ELECTRON MICROSCOPY.Cytoplasmic Streaming: The movement of CYTOPLASM within a CELL. It serves as an internal transport system for moving essential substances throughout the cell, and in single-celled organisms, such as the AMOEBA, it is responsible for the movement (CELL MOVEMENT) of the entire cell.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Protein Structure, Tertiary: The level of protein structure in which combinations of secondary protein structures (alpha helices, beta sheets, loop regions, and motifs) pack together to form folded shapes called domains. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Small proteins usually consist of only one domain but larger proteins may contain a number of domains connected by segments of polypeptide chain which lack regular secondary structure.Mechanotransduction, Cellular: The process by which cells convert mechanical stimuli into a chemical response. It can occur in both cells specialized for sensing mechanical cues such as MECHANORECEPTORS, and in parenchymal cells whose primary function is not mechanosensory.Heart Block: Impaired conduction of cardiac impulse that can occur anywhere along the conduction pathway, such as between the SINOATRIAL NODE and the right atrium (SA block) or between atria and ventricles (AV block). Heart blocks can be classified by the duration, frequency, or completeness of conduction block. Reversibility depends on the degree of structural or functional defects.Cilia: Populations of thin, motile processes found covering the surface of ciliates (CILIOPHORA) or the free surface of the cells making up ciliated EPITHELIUM. Each cilium arises from a basic granule in the superficial layer of CYTOPLASM. The movement of cilia propels ciliates through the liquid in which they live. The movement of cilia on a ciliated epithelium serves to propel a surface layer of mucus or fluid. (King & Stansfield, A Dictionary of Genetics, 4th ed)Nerve Fibers: Slender processes of NEURONS, including the AXONS and their glial envelopes (MYELIN SHEATH). Nerve fibers conduct nerve impulses to and from the CENTRAL NERVOUS SYSTEM.Cochlea: The part of the inner ear (LABYRINTH) that is concerned with hearing. It forms the anterior part of the labyrinth, as a snail-like structure that is situated almost horizontally anterior to the VESTIBULAR LABYRINTH.Cardiac Pacing, Artificial: Regulation of the rate of contraction of the heart muscles by an artificial pacemaker.Protein Conformation: The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).Mesophyll Cells: Large and highly vacuolated cells possessing many chloroplasts occuring in the interior cross-section of leaves, juxtaposed between the epidermal layers.Ajmaline: An alkaloid found in the root of RAUWOLFIA SERPENTINA, among other plant sources. It is a class Ia antiarrhythmic agent that apparently acts by changing the shape and threshold of cardiac action potentials.Myosins: A diverse superfamily of proteins that function as translocating proteins. They share the common characteristics of being able to bind ACTINS and hydrolyze MgATP. Myosins generally consist of heavy chains which are involved in locomotion, and light chains which are involved in regulation. Within the structure of myosin heavy chain are three domains: the head, the neck and the tail. The head region of the heavy chain contains the actin binding domain and MgATPase domain which provides energy for locomotion. The neck region is involved in binding the light-chains. The tail region provides the anchoring point that maintains the position of the heavy chain. The superfamily of myosins is organized into structural classes based upon the type and arrangement of the subunits they contain.Ear, Inner: The essential part of the hearing organ consists of two labyrinthine compartments: the bony labyrinthine and the membranous labyrinth. The bony labyrinth is a complex of three interconnecting cavities or spaces (COCHLEA; VESTIBULAR LABYRINTH; and SEMICIRCULAR CANALS) in the TEMPORAL BONE. Within the bony labyrinth lies the membranous labyrinth which is a complex of sacs and tubules (COCHLEAR DUCT; SACCULE AND UTRICLE; and SEMICIRCULAR DUCTS) forming a continuous space enclosed by EPITHELIUM and connective tissue. These spaces are filled with LABYRINTHINE FLUIDS of various compositions.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Pseudopodia: A dynamic actin-rich extension of the surface of an animal cell used for locomotion or prehension of food.Anterior Cruciate Ligament: A strong ligament of the knee that originates from the posteromedial portion of the lateral condyle of the femur, passes anteriorly and inferiorly between the condyles, and attaches to the depression in front of the intercondylar eminence of the tibia.Biomechanical Phenomena: The properties, processes, and behavior of biological systems under the action of mechanical forces.Protein Binding: The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.TurtlesCrystallography, X-Ray: The study of crystal structure using X-RAY DIFFRACTION techniques. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Axons: Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body.Phalloidine: Very toxic polypeptide isolated mainly from AMANITA phalloides (Agaricaceae) or death cup; causes fatal liver, kidney and CNS damage in mushroom poisoning; used in the study of liver damage.Actinin: A protein factor that regulates the length of R-actin. It is chemically similar, but immunochemically distinguishable from actin.Vinculin: A cytoskeletal protein associated with cell-cell and cell-matrix interactions. The amino acid sequence of human vinculin has been determined. The protein consists of 1066 amino acid residues and its gene has been assigned to chromosome 10.Hemerythrin: A non-heme iron protein consisting of eight apparently identical subunits each containing 2 iron atoms. It binds one molecule of oxygen per pair of iron atoms and functions as a respiratory protein.Hair Cells, Auditory, Outer: Sensory cells of organ of Corti. In mammals, they are usually arranged in three or four rows, and away from the core of spongy bone (the modiolus), lateral to the INNER AUDITORY HAIR CELLS and other supporting structures. Their cell bodies and STEREOCILIA increase in length from the cochlear base toward the apex and laterally across the rows, allowing differential responses to various frequencies of sound.Microscopy, Fluorescence: Microscopy of specimens stained with fluorescent dye (usually fluorescein isothiocyanate) or of naturally fluorescent materials, which emit light when exposed to ultraviolet or blue light. Immunofluorescence microscopy utilizes antibodies that are labeled with fluorescent dye.Organ of Corti: The spiral EPITHELIUM containing sensory AUDITORY HAIR CELLS and supporting cells in the cochlea. Organ of Corti, situated on the BASILAR MEMBRANE and overlaid by a gelatinous TECTORIAL MEMBRANE, converts sound-induced mechanical waves to neural impulses to the brain.Tubulin: A microtubule subunit protein found in large quantities in mammalian brain. It has also been isolated from SPERM FLAGELLUM; CILIA; and other sources. Structurally, the protein is a dimer with a molecular weight of approximately 120,000 and a sedimentation coefficient of 5.8S. It binds to COLCHICINE; VINCRISTINE; and VINBLASTINE.Plant Leaves: Expanded structures, usually green, of vascular plants, characteristically consisting of a bladelike expansion attached to a stem, and functioning as the principal organ of photosynthesis and transpiration. (American Heritage Dictionary, 2d ed)Fluorescent Antibody Technique: Test for tissue antigen using either a direct method, by conjugation of antibody with fluorescent dye (FLUORESCENT ANTIBODY TECHNIQUE, DIRECT) or an indirect method, by formation of antigen-antibody complex which is then labeled with fluorescein-conjugated anti-immunoglobulin antibody (FLUORESCENT ANTIBODY TECHNIQUE, INDIRECT). The tissue is then examined by fluorescence microscopy.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Protein Folding: Processes involved in the formation of TERTIARY PROTEIN STRUCTURE.Nerve Fibers, Myelinated: A class of nerve fibers as defined by their structure, specifically the nerve sheath arrangement. The AXONS of the myelinated nerve fibers are completely encased in a MYELIN SHEATH. They are fibers of relatively large and varied diameters. Their NEURAL CONDUCTION rates are faster than those of the unmyelinated nerve fibers (NERVE FIBERS, UNMYELINATED). Myelinated nerve fibers are present in somatic and autonomic nerves.Chickens: Common name for the species Gallus gallus, the domestic fowl, in the family Phasianidae, order GALLIFORMES. It is descended from the red jungle fowl of SOUTHEAST ASIA.Subtilisin: A serine endopeptidase isolated from Bacillus subtilis. It hydrolyzes proteins with broad specificity for peptide bonds, and a preference for a large uncharged residue in P1. It also hydrolyzes peptide amides. (From Enzyme Nomenclature, 1992) EC 3.4.21.62.Accessory Atrioventricular Bundle: Extra impulse-conducting tissue in the heart that creates abnormal impulse-conducting connections between HEART ATRIA and HEART VENTRICLES.Hearing: The ability or act of sensing and transducing ACOUSTIC STIMULATION to the CENTRAL NERVOUS SYSTEM. It is also called audition.Computer Simulation: Computer-based representation of physical systems and phenomena such as chemical processes.Tendons: Fibrous bands or cords of CONNECTIVE TISSUE at the ends of SKELETAL MUSCLE FIBERS that serve to attach the MUSCLES to bones and other structures.Heart Septum: This structure includes the thin muscular atrial septum between the two HEART ATRIA, and the thick muscular ventricular septum between the two HEART VENTRICLES.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.Electrophysiologic Techniques, Cardiac: Methods to induce and measure electrical activities at specific sites in the heart to diagnose and treat problems with the heart's electrical system.HIV Envelope Protein gp41: Transmembrane envelope protein of the HUMAN IMMUNODEFICIENCY VIRUS which is encoded by the HIV env gene. It has a molecular weight of 41,000 and is glycosylated. The N-terminal part of gp41 is thought to be involved in CELL FUSION with the CD4 ANTIGENS of T4 LYMPHOCYTES, leading to syncytial formation. Gp41 is one of the most common HIV antigens detected by IMMUNOBLOTTING.Flaveria: A plant genus of the family ASTERACEAE that is used for experiments in molecular genetic studies in plant physiology and development.Horseshoe Crabs: An arthropod subclass (Xiphosura) comprising the North American (Limulus) and Asiatic (Tachypleus) genera of horseshoe crabs.Cadaver: A dead body, usually a human body.Self Stimulation: Stimulation of the brain, which is self-administered. The stimulation may result in negative or positive reinforcement.Carrier Proteins: Transport proteins that carry specific substances in the blood or across cell membranes.Stress, Mechanical: A purely physical condition which exists within any material because of strain or deformation by external forces or by non-uniform thermal expansion; expressed quantitatively in units of force per unit area.Circular Dichroism: A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Tachycardia, Atrioventricular Nodal Reentry: Abnormally rapid heartbeats caused by reentry of atrial impulse into the dual (fast and slow) pathways of ATRIOVENTRICULAR NODE. The common type involves a blocked atrial impulse in the slow pathway which reenters the fast pathway in a retrograde direction and simultaneously conducts to the atria and the ventricles leading to rapid HEART RATE of 150-250 beats per minute.Binding Sites: The parts of a macromolecule that directly participate in its specific combination with another molecule.Catheter Ablation: Removal of tissue with electrical current delivered via electrodes positioned at the distal end of a catheter. Energy sources are commonly direct current (DC-shock) or alternating current at radiofrequencies (usually 750 kHz). The technique is used most often to ablate the AV junction and/or accessory pathways in order to interrupt AV conduction and produce AV block in the treatment of various tachyarrhythmias.Microtubule-Associated Proteins: High molecular weight proteins found in the MICROTUBULES of the cytoskeletal system. Under certain conditions they are required for TUBULIN assembly into the microtubules and stabilize the assembled microtubules.Endolymph: The lymph fluid found in the membranous labyrinth of the ear. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Movement: The act, process, or result of passing from one place or position to another. It differs from LOCOMOTION in that locomotion is restricted to the passing of the whole body from one place to another, while movement encompasses both locomotion but also a change of the position of the whole body or any of its parts. Movement may be used with reference to humans, vertebrate and invertebrate animals, and microorganisms. Differentiate also from MOTOR ACTIVITY, movement associated with behavior.Intermediate Filaments: Cytoplasmic filaments intermediate in diameter (about 10 nanometers) between the microfilaments and the microtubules. They may be composed of any of a number of different proteins and form a ring around the cell nucleus.Zea mays: A plant species of the family POACEAE. It is a tall grass grown for its EDIBLE GRAIN, corn, used as food and animal FODDER.Purkinje Fibers: Modified cardiac muscle fibers composing the terminal portion of the heart conduction system.Mechanoreceptors: Cells specialized to transduce mechanical stimuli and relay that information centrally in the nervous system. Mechanoreceptor cells include the INNER EAR hair cells, which mediate hearing and balance, and the various somatosensory receptors, often with non-neural accessory structures.Protein Structure, Quaternary: The characteristic 3-dimensional shape and arrangement of multimeric proteins (aggregates of more than one polypeptide chain).Immunohistochemistry: Histochemical localization of immunoreactive substances using labeled antibodies as reagents.Cytoplasm: The part of a cell that contains the CYTOSOL and small structures excluding the CELL NUCLEUS; MITOCHONDRIA; and large VACUOLES. (Glick, Glossary of Biochemistry and Molecular Biology, 1990)Heart Atria: The chambers of the heart, to which the BLOOD returns from the circulation.Electrophysiology: The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.Regression (Psychology): A return to earlier, especially to infantile, patterns of thought or behavior, or stage of functioning, e.g., feelings of helplessness and dependency in a patient with a serious physical illness. (From APA, Thesaurus of Psychological Index Terms, 1994).Plant Stems: Parts of plants that usually grow vertically upwards towards the light and support the leaves, buds, and reproductive structures. (From Concise Dictionary of Biology, 1990)Anisotropy: A physical property showing different values in relation to the direction in or along which the measurement is made. The physical property may be with regard to thermal or electric conductivity or light refraction. In crystallography, it describes crystals whose index of refraction varies with the direction of the incident light. It is also called acolotropy and colotropy. The opposite of anisotropy is isotropy wherein the same values characterize the object when measured along axes in all directions.Rabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Calcium: A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.Microscopy, Confocal: A light microscopic technique in which only a small spot is illuminated and observed at a time. An image is constructed through point-by-point scanning of the field in this manner. Light sources may be conventional or laser, and fluorescence or transmitted observations are possible.Pupa: An inactive stage between the larval and adult stages in the life cycle of insects.Microscopy, Electron, Transmission: Electron microscopy in which the ELECTRONS or their reaction products that pass down through the specimen are imaged below the plane of the specimen.Microvilli: Minute projections of cell membranes which greatly increase the surface area of the cell.Dogs: The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)Anterior Cruciate Ligament Reconstruction: Rebuilding of the ANTERIOR CRUCIATE LIGAMENT to restore functional stability of the knee. AUTOGRAFTING or ALLOGRAFTING of tissues is often used.Diffusion Tensor Imaging: The use of diffusion ANISOTROPY data from diffusion magnetic resonance imaging results to construct images based on the direction of the faster diffusing molecules.Cell Membrane: The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.Cytoskeletal Proteins: Major constituent of the cytoskeleton found in the cytoplasm of eukaryotic cells. They form a flexible framework for the cell, provide attachment points for organelles and formed bodies, and make communication between parts of the cell possible.Tachycardia: Abnormally rapid heartbeat, usually with a HEART RATE above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia.Sequence Homology, Amino Acid: The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.Neural Pathways: Neural tracts connecting one part of the nervous system with another.Microscopy, Immunoelectron: Microscopy in which the samples are first stained immunocytochemically and then examined using an electron microscope. Immunoelectron microscopy is used extensively in diagnostic virology as part of very sensitive immunoassays.Organoids: An organization of cells into an organ-like structure. Organoids can be generated in culture. They are also found in certain neoplasms.Cytochalasins: 11- to 14-membered macrocyclic lactones with a fused isoindolone. Members with INDOLES attached at the C10 position are called chaetoglobosins. They are produced by various fungi. Some members interact with ACTIN and inhibit CYTOKINESIS.HIV Fusion Inhibitors: Inhibitors of the fusion of HIV to host cells, preventing viral entry. This includes compounds that block attachment of HIV ENVELOPE PROTEIN GP120 to CD4 RECEPTORS.Membrane Proteins: Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.Muscle, Smooth: Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)Phloem: Plant tissue that carries nutrients, especially sucrose, by turgor pressure. Movement is bidirectional, in contrast to XYLEM where it is only upward. Phloem originates and grows outwards from meristematic cells (MERISTEM) in the vascular cambium. P-proteins, a type of LECTINS, are characteristically found in phloem.Chick Embryo: The developmental entity of a fertilized chicken egg (ZYGOTE). The developmental process begins about 24 h before the egg is laid at the BLASTODISC, a small whitish spot on the surface of the EGG YOLK. After 21 days of incubation, the embryo is fully developed before hatching.Dimerization: The process by which two molecules of the same chemical composition form a condensation product or polymer.Dihydrostreptomycin Sulfate: A semi-synthetic aminoglycoside antibiotic that is used in the treatment of TUBERCULOSIS.Diffusion Magnetic Resonance Imaging: A diagnostic technique that incorporates the measurement of molecular diffusion (such as water or metabolites) for tissue assessment by MRI. The degree of molecular movement can be measured by changes of apparent diffusion coefficient (ADC) with time, as reflected by tissue microstructure. Diffusion MRI has been used to study BRAIN ISCHEMIA and tumor response to treatment.Muscle Contraction: A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.Elasticity: Resistance and recovery from distortion of shape.Kinetics: The rate dynamics in chemical or physical systems.Peptides: Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are linear polypeptides that are normally synthesized on RIBOSOMES.Connective Tissue: Tissue that supports and binds other tissues. It consists of CONNECTIVE TISSUE CELLS embedded in a large amount of EXTRACELLULAR MATRIX.Myosin Type II: The subfamily of myosin proteins that are commonly found in muscle fibers. Myosin II is also involved a diverse array of cellular functions including cell division, transport within the GOLGI APPARATUS, and maintaining MICROVILLI structure.Cell Polarity: Orientation of intracellular structures especially with respect to the apical and basolateral domains of the plasma membrane. Polarized cells must direct proteins from the Golgi apparatus to the appropriate domain since tight junctions prevent proteins from diffusing between the two domains.Electric Stimulation: Use of electric potential or currents to elicit biological responses.Atrial Function: The hemodynamic and electrophysiological action of the HEART ATRIA.Heart Ventricles: The lower right and left chambers of the heart. The right ventricle pumps venous BLOOD into the LUNGS and the left ventricle pumps oxygenated blood into the systemic arterial circulation.Agenesis of Corpus Callosum: Birth defect that results in a partial or complete absence of the CORPUS CALLOSUM. It may be isolated or a part of a syndrome (e.g., AICARDI'S SYNDROME; ACROCALLOSAL SYNDROME; ANDERMANN SYNDROME; and HOLOPROSENCEPHALY). Clinical manifestations include neuromotor skill impairment and INTELLECTUAL DISABILITY of variable severity.Physical Stimulation: Act of eliciting a response from a person or organism through physical contact.Tachycardia, Paroxysmal: Abnormally rapid heartbeats with sudden onset and cessation.Motion: Physical motion, i.e., a change in position of a body or subject as a result of an external force. It is distinguished from MOVEMENT, a process resulting from biological activity.Image Processing, Computer-Assisted: A technique of inputting two-dimensional images into a computer and then enhancing or analyzing the imagery into a form that is more useful to the human observer.Microscopy, Interference: The science and application of a double-beam transmission interference microscope in which the illuminating light beam is split into two paths. One beam passes through the specimen while the other beam reflects off a reference mirror before joining and interfering with the other. The observed optical path difference between the two beams can be measured and used to discriminate minute differences in thickness and refraction of non-stained transparent specimens, such as living cells in culture.Myofibrils: The long cylindrical contractile organelles of STRIATED MUSCLE cells composed of ACTIN FILAMENTS; MYOSIN filaments; and other proteins organized in arrays of repeating units called SARCOMERES .Microscopy, Video: Microscopy in which television cameras are used to brighten magnified images that are otherwise too dark to be seen with the naked eye. It is used frequently in TELEPATHOLOGY.Nuclear Magnetic Resonance, Biomolecular: NMR spectroscopy on small- to medium-size biological macromolecules. This is often used for structural investigation of proteins and nucleic acids, and often involves more than one isotope.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Collagen: A polypeptide substance comprising about one third of the total protein in mammalian organisms. It is the main constituent of SKIN; CONNECTIVE TISSUE; and the organic substance of bones (BONE AND BONES) and teeth (TOOTH).Posterior Cruciate Ligament: A strong ligament of the knee that originates from the anterolateral surface of the medial condyle of the femur, passes posteriorly and inferiorly between the condyles, and attaches to the posterior intercondylar area of the tibia.Ganglion Cysts: Nodular tumor-like lesions or mucoid flesh, arising from tendon sheaths, LIGAMENTS, or JOINT CAPSULE, especially of the hands, wrists, or feet. They are not true cysts as they lack epithelial wall. They are distinguished from SYNOVIAL CYSTS by the lack of communication with a joint cavity or the SYNOVIAL MEMBRANE.Protein Multimerization: The assembly of the QUATERNARY PROTEIN STRUCTURE of multimeric proteins (MULTIPROTEIN COMPLEXES) from their composite PROTEIN SUBUNITS.Thermodynamics: A rigorously mathematical analysis of energy relationships (heat, work, temperature, and equilibrium). It describes systems whose states are determined by thermal parameters, such as temperature, in addition to mechanical and electromagnetic parameters. (From Hawley's Condensed Chemical Dictionary, 12th ed)Intercellular Junctions: Direct contact of a cell with a neighboring cell. Most such junctions are too small to be resolved by light microscopy, but they can be visualized by conventional or freeze-fracture electron microscopy, both of which show that the interacting CELL MEMBRANE and often the underlying CYTOPLASM and the intervening EXTRACELLULAR SPACE are highly specialized in these regions. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p792)Tachycardia, Ventricular: An abnormally rapid ventricular rhythm usually in excess of 150 beats per minute. It is generated within the ventricle below the BUNDLE OF HIS, either as autonomic impulse formation or reentrant impulse conduction. Depending on the etiology, onset of ventricular tachycardia can be paroxysmal (sudden) or nonparoxysmal, its wide QRS complexes can be uniform or polymorphic, and the ventricular beating may be independent of the atrial beating (AV dissociation).Coronary Sinus: A short vein that collects about two thirds of the venous blood from the MYOCARDIUM and drains into the RIGHT ATRIUM. Coronary sinus, normally located between the LEFT ATRIUM and LEFT VENTRICLE on the posterior surface of the heart, can serve as an anatomical reference for cardiac procedures.Membrane Fusion: The adherence and merging of cell membranes, intracellular membranes, or artificial membranes to each other or to viruses, parasites, or interstitial particles through a variety of chemical and physical processes.Actomyosin: A protein complex of actin and MYOSINS occurring in muscle. It is the essential contractile substance of muscle.Ion Channels: Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.Bacterial Proteins: Proteins found in any species of bacterium.Cell Movement: The movement of cells from one location to another. Distinguish from CYTOKINESIS which is the process of dividing the CYTOPLASM of a cell.Plant Epidermis: A thin layer of cells forming the outer integument of seed plants and ferns. (Random House Unabridged Dictionary, 2d ed)Ophthalmic Nerve: A sensory branch of the trigeminal (5th cranial) nerve. The ophthalmic nerve carries general afferents from the superficial division of the face including the eyeball, conjunctiva, upper eyelid, upper nose, nasal mucosa, and scalp.Muscles: Contractile tissue that produces movement in animals.Phosphoenolpyruvate Carboxylase: An enzyme with high affinity for carbon dioxide. It catalyzes irreversibly the formation of oxaloacetate from phosphoenolpyruvate and carbon dioxide. This fixation of carbon dioxide in several bacteria and some plants is the first step in the biosynthesis of glucose. EC 4.1.1.31.Biopolymers: Polymers synthesized by living organisms. They play a role in the formation of macromolecular structures and are synthesized via the covalent linkage of biological molecules, especially AMINO ACIDS; NUCLEOTIDES; and CARBOHYDRATES.Molecular Motor Proteins: Proteins that are involved in or cause CELL MOVEMENT such as the rotary structures (flagellar motor) or the structures whose movement is directed along cytoskeletal filaments (MYOSIN; KINESIN; and DYNEIN motor families).Photosynthesis: The synthesis by organisms of organic chemical compounds, especially carbohydrates, from carbon dioxide using energy obtained from light rather than from the oxidation of chemical compounds. Photosynthesis comprises two separate processes: the light reactions and the dark reactions. In higher plants; GREEN ALGAE; and CYANOBACTERIA; NADPH and ATP formed by the light reactions drive the dark reactions which result in the fixation of carbon dioxide. (from Oxford Dictionary of Biochemistry and Molecular Biology, 2001)Actin-Related Protein 2-3 Complex: A complex of seven proteins including ARP2 PROTEIN and ARP3 PROTEIN that plays an essential role in maintenance and assembly of the CYTOSKELETON. Arp2-3 complex binds WASP PROTEIN and existing ACTIN FILAMENTS, and it nucleates the formation of new branch point filaments.Cytochalasin B: A cytotoxic member of the CYTOCHALASINS.Sequence Alignment: The arrangement of two or more amino acid or base sequences from an organism or organisms in such a way as to align areas of the sequences sharing common properties. The degree of relatedness or homology between the sequences is predicted computationally or statistically based on weights assigned to the elements aligned between the sequences. This in turn can serve as a potential indicator of the genetic relatedness between the organisms.Polymers: Compounds formed by the joining of smaller, usually repeating, units linked by covalent bonds. These compounds often form large macromolecules (e.g., BIOPOLYMERS; PLASTICS).Contractile Proteins: Proteins which participate in contractile processes. They include MUSCLE PROTEINS as well as those found in other cells and tissues. In the latter, these proteins participate in localized contractile events in the cytoplasm, in motile activity, and in cell aggregation phenomena.Oxidopamine: A neurotransmitter analogue that depletes noradrenergic stores in nerve endings and induces a reduction of dopamine levels in the brain. Its mechanism of action is related to the production of cytolytic free-radicals.Recombinant Fusion Proteins: Recombinant proteins produced by the GENETIC TRANSLATION of fused genes formed by the combination of NUCLEIC ACID REGULATORY SEQUENCES of one or more genes with the protein coding sequences of one or more genes.Catheter-Related Infections: Infections resulting from the use of catheters. Proper aseptic technique, site of catheter placement, material composition, and virulence of the organism are all factors that can influence possible infection.Vectorcardiography: Recording of the moment-to-moment electromotive forces of the heart on a plane of the body surface delineated as a vector function of time.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Wolff-Parkinson-White Syndrome: A form of ventricular pre-excitation characterized by a short PR interval and a long QRS interval with a delta wave. In this syndrome, atrial impulses are abnormally conducted to the HEART VENTRICLES via an ACCESSORY CONDUCTING PATHWAY that is located between the wall of the right or left atria and the ventricles, also known as a BUNDLE OF KENT. The inherited form can be caused by mutation of PRKAG2 gene encoding a gamma-2 regulatory subunit of AMP-activated protein kinase.Cardiac Resynchronization Therapy: The restoration of the sequential order of contraction and relaxation of the HEART ATRIA and HEART VENTRICLES by atrio-biventricular pacing.Recombinant Proteins: Proteins prepared by recombinant DNA technology.Magnetic Resonance Spectroscopy: Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).Fibroblasts: Connective tissue cells which secrete an extracellular matrix rich in collagen and other macromolecules.Cytochalasin D: A fungal metabolite that blocks cytoplasmic cleavage by blocking formation of contractile microfilament structures resulting in multinucleated cell formation, reversible inhibition of cell movement, and the induction of cellular extrusion. Additional reported effects include the inhibition of actin polymerization, DNA synthesis, sperm motility, glucose transport, thyroid secretion, and growth hormone release.Gelsolin: A 90-kDa protein produced by macrophages that severs ACTIN filaments and forms a cap on the newly exposed filament end. Gelsolin is activated by CALCIUM ions and participates in the assembly and disassembly of actin, thereby increasing the motility of some CELLS.Amino Acid Motifs: Commonly observed structural components of proteins formed by simple combinations of adjacent secondary structures. A commonly observed structure may be composed of a CONSERVED SEQUENCE which can be represented by a CONSENSUS SEQUENCE.Muscle Fibers, Skeletal: Large, multinucleate single cells, either cylindrical or prismatic in shape, that form the basic unit of SKELETAL MUSCLE. They consist of MYOFIBRILS enclosed within and attached to the SARCOLEMMA. They are derived from the fusion of skeletal myoblasts (MYOBLASTS, SKELETAL) into a syncytium, followed by differentiation.Hydrophobic and Hydrophilic Interactions: The thermodynamic interaction between a substance and WATER.Protein Stability: The ability of a protein to retain its structural conformation or its activity when subjected to physical or chemical manipulations.Green Fluorescent Proteins: Protein analogs and derivatives of the Aequorea victoria green fluorescent protein that emit light (FLUORESCENCE) when excited with ULTRAVIOLET RAYS. They are used in REPORTER GENES in doing GENETIC TECHNIQUES. Numerous mutants have been made to emit other colors or be sensitive to pH.Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.Epithelium: One or more layers of EPITHELIAL CELLS, supported by the basal lamina, which covers the inner or outer surfaces of the body.Neurons: The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.Action Potentials: Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.Nursing, Team: Coordination of nursing services by various nursing care personnel under the leadership of a professional nurse. The team may consist of a professional nurse, nurses' aides, and the practical nurse.Cell Surface Extensions: Specialized structures of the cell that extend the cell membrane and project out from the cell surface.Light: That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.Elastic Tissue: Connective tissue comprised chiefly of elastic fibers. Elastic fibers have two components: ELASTIN and MICROFIBRILS.Heart: The hollow, muscular organ that maintains the circulation of the blood.Tectorial Membrane: A membrane, attached to the bony SPIRAL LAMINA, overlying and coupling with the hair cells of the ORGAN OF CORTI in the inner ear. It is a glycoprotein-rich keratin-like layer containing fibrils embedded in a dense amorphous substance.Structural Homology, Protein: The degree of 3-dimensional shape similarity between proteins. It can be an indication of distant AMINO ACID SEQUENCE HOMOLOGY and used for rational DRUG DESIGN.Temperature: The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.Spindle Apparatus: A microtubule structure that forms during CELL DIVISION. It consists of two SPINDLE POLES, and sets of MICROTUBULES that may include the astral microtubules, the polar microtubules, and the kinetochore microtubules.Guinea Pigs: A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.Mechanical Processes: The behaviors of materials under force.Birefringence: The property of nonisotropic media, such as crystals, whereby a single incident beam of light traverses the medium as two beams, each plane-polarized, the planes being at right angles to each other. (Cline et al., Dictionary of Visual Science, 4th ed)Chloroplasts: Plant cell inclusion bodies that contain the photosynthetic pigment CHLOROPHYLL, which is associated with the membrane of THYLAKOIDS. Chloroplasts occur in cells of leaves and young stems of plants. They are also found in some forms of PHYTOPLANKTON such as HAPTOPHYTA; DINOFLAGELLATES; DIATOMS; and CRYPTOPHYTA.Myosin Type III: A subclass of myosins originally found in the photoreceptor of DROSOPHILA. The heavy chains can occur as two alternatively spliced isoforms of 132 and 174 KDa. The amino terminal of myosin type III is highly unusual in that it contains a protein kinase domain which may be an important component of the visual process.Otolithic Membrane: A gelatinous membrane overlying the acoustic maculae of SACCULE AND UTRICLE. It contains minute crystalline particles (otoliths) of CALCIUM CARBONATE and protein on its outer surface. In response to head movement, the otoliths shift causing distortion of the vestibular hair cells which transduce nerve signals to the BRAIN for interpretation of equilibrium.Alamethicin: A cyclic nonadecapeptide antibiotic that can act as an ionophore and is produced by strains of Trichoderma viride. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)Gene Expression Regulation, Plant: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action in plants.

Hierarchy of ventricular pacemakers. (1/251)

To characterize the pattern of pacemaker dominance in the ventricular specialized conduction system (VSCS), escape ventricular pacemakers were localized and quantified in vivo and in virto, in normal hearts and in hearts 24 hours after myocardial infarction. Excape pacemaker foci were localized in vivo during vagally induced atrial arrest by means of electrograms recorded from the His bundle and proximal bundle branches and standard electrocardiographic limb leads. The VSCS was isolated using a modified Elizari preparation or preparations of each bundle branch. Peacemakers were located by extra- and intracellular recordings. Escape pacemaker foci in vivo were always in the proximal conduction system, usually the left bundle branch. The rate was 43+/-11 (mean+/-SD) beats/min. After beta-adrenergic blockade, the mean rate fell to 31+/-10 beats/min, but there were no shifts in pacemaker location. In the infarcted hearts, pacemakers were located in the peripheral left bundle branch. The mean rate was 146+/-20 beats/min. In isolated normal preparations, the dominant pacemakers usually were in the His bundle, firing at a mean rate of 43+/-10 beats/min. The rates of pacemakers diminished with distal progression. In infarcted hearts, the pacemakers invariably were in the infarct zone. The mean firing rates were not influenced by beta-adrenergic blockade. The results indicate that the dominant pacemakers are normally in the very proximal VSCS, but after myocardial infarction pacemaker dominance is shifted into the infarct. Distribution of pacemaker dominance is independent of sympathetic influence.  (+info)

Modulation of AV nodal and Hisian conduction by changes in extracellular space. (2/251)

Previous studies have demonstrated that the extracellular space (ECS) component of the atrioventricular (AV) node and His bundle region is larger than the ECS in adjacent contractile myocardium. The potential physiological significance of this observation was examined in a canine blood-perfused AV nodal preparation. Mannitol, an ECS osmotic expander, was infused directly into either the AV node or His bundle region. This resulted in a significant dose-dependent increase in the AV nodal or His-ventricular conduction time and in the AV nodal effective refractory period. Mannitol infusion eventually resulted in Wenckebach block (n = 6), which reversed with mannitol washout. The ratio of AV nodal to left ventricular ECS in tissue frozen immediately on the development of heart block (n = 8) was significantly higher in the region of block (4.53 +/- 0.61) compared with that in control preparations (2.23 +/- 0.35, n = 6, P < 0.01) and donor dog hearts (2.45 +/- 0.18, n = 11, P < 0.01) not exposed to mannitol. With lower mannitol rates (10% of total blood flow), AV nodal conduction times increased by 5-10% and the AV node became supersensitive to adenosine, acetylcholine, and carbachol, but not to norepinephrine. We conclude that mannitol-induced changes in AV node and His bundle ECS markedly alter conduction system electrophysiology and the sensitivity of conductive tissues to purinergic and cholinergic agonists.  (+info)

LocaLisa: new technique for real-time 3-dimensional localization of regular intracardiac electrodes. (3/251)

BACKGROUND: Estimation of the 3-dimensional (3D) position of ablation electrodes from fluoroscopic images is inadequate if a systematic lesion pattern is required in the treatment of complex arrhythmogenic substrates. METHODS AND RESULTS: We developed a new technique for online 3D localization of intracardiac electrodes. Regular catheter electrodes are used as sensors for a high-frequency transthoracic electrical field, which is applied via standard skin electrodes. We investigated localization accuracy within the right atrium, right ventricle, and left ventricle by comparing measured and true interelectrode distances of a decapolar catheter. Long-term stability was analyzed by localization of the most proximal His bundle before and after slow pathway ablation. Electrogram recordings were unaffected by the applied electrical field. Localization data from 3 catheter positions, widely distributed within the right atrium, right ventricle, or left ventricle, were analyzed in 10 patients per group. The relationship between measured and true electrode positions was highly linear, with an average correlation coefficient of 0.996, 0.997, and 0.999 for the right atrium, right ventricle, and left ventricle, respectively. Localization accuracy was better than 2 mm, with an additional scaling error of 8% to 14%. After 2 hours, localization of the proximal His bundle was reproducible within 1.4+/-1.1 mm. CONCLUSIONS: This new technique enables accurate and reproducible real-time localization of electrode positions in cardiac mapping and ablation procedures. Its application does not distort the quality of electrograms and can be applied to any electrode catheter.  (+info)

Reversion to sinus rhythm 11 years after surgically induced heart block. (4/251)

A patient is presented in whom the heart reverted spontaneously to sinus rhythm 11 years after surgical closure of a ventricular septal defect complicated by complete heart block. It seems unlikely that regeneration of fibres in the bundle of His, if these had indeed been destroyed, could account for the restoration of sinus rhythm after so long an interval.  (+info)

Electrophysiological effects of mexiletine in man. (5/251)

The electrophysiological effects of intravenous mexiletine in a dose of 200 to 250 mg given over 5 minutes, followed by continuous infusion of 60 to 90 mg per hour, were studied in 5 patients with normal conduction and in 20 patients with a variety of disturbances of impulse formation and conduction, by means of His bundle electrography, atrial pacing, and the extrastimulus method. In all but 2 patients the plasma level was above the lower therapeutic limit. Mexiletine had no consistent effects on sinus frequency and atrial refractoriness. The sinoatrial recovery time changed inconsistently in both directions; however, of the 5 patients in whom an increase was evident, 3 had sinus node dysfunction. In most patients mexiletine increased the AV nodal conduction time at paced atrial rates and shifted the Wenckebach point to a lower atrial rate. The effective refractory period of the AV node was not consistently influenced, while the functional refractory period increased in 12 out of 14 patients. The HV intervals increased by a mean of 11 ms in 8 patients and were unchanged in 17. Both the relative and effective refractory period of the His-Purkinje system increased after mexiletine. Non-cardiac side effects occurred in 7 out of 25 patients, and cardiac side effects, including one serious, in 2. The results indicate that mexiletine shares some electrophysiological properties with procainamide and quinidine, when given to patients with conduction defects, and that the drug should not be used in patients with pre-existing impairment of impulse formation or conduction. It has additional effects on AV nodal conduction which may be of value in the treatment of re-entrant tachycardias involving the AV node.  (+info)

Chronic His bundle block. Clinical, electrocardiographic, electrophysiological, and follow-up studies on 16 patients. (6/251)

This report describes 16 patients with block within the His bundle seen over a period of 55 months. Ten were women and 6 men, with an average age of 76 years, range, 42 to 98 years. All patients had His bundle recordings showing split His bundle potentials (H and H) (13 patients) or narrow QRS with block distal to the His bundle potential (3 patients). Of the 16 patients, 10 had complete heart block, 4 second degree AV block (2 patients with Mobitz type II, and 2 with 2:1), and 2 first degree AV block. Ten patients had a narrow QRS in the conducted beats or escape rhythms. Intravenous atropine (1 to 2 mg) had a variable effect on AV conduction and the rate of the escape rhythm. Twelve patients have had a permanent pacemaker implanted. During the follow-up period, 10 patients died 1 to 31 months from the time of initial examination. The remaining 6 patients (5 with pacemaker) are alive 3 to 58 months later.  (+info)

Living anatomy of the atrioventricular junctions. A guide to electrophysiologic mapping. A Consensus Statement from the Cardiac Nomenclature Study Group, Working Group of Arrhythmias, European Society of Cardiology, and the Task Force on Cardiac Nomenclature from NASPE. (7/251)

Current nomenclature for the atrioventricular (AV) junctions derives from a surgically distorted view, placing the valvar rings and the triangle of Koch in a single plane with antero-posterior and right-left lateral coordinates. Within this convention, the aorta is considered to occupy an anterior position, although the mouth of the coronary sinus is shown as being posterior. Although this nomenclature has served its purpose for the description and treatment of arrhythmias dependent on accessory pathways and atrioventricular nodal reentry, it is less than satisfactory for the description of atrial and ventricular mapping. To correct these deficiencies, a consensus document has been prepared by experts from the Working Group of Arrhythmias of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. It proposes a new anatomically sound nomenclature that will be applicable to all chambers of the heart. In this report, we discuss its value for description of the AV junctions, establishing the principles of this new nomenclature.  (+info)

Double component action potentials in the posterior approach to the atrioventricular node: do they reflect activation delay in the slow pathway? (8/251)

OBJECTIVES: The aim of the study was to elucidate the mechanism of double component action potentials in the posterior approach to the atrioventricular (AV) junctional area. BACKGROUND: Double component action potentials are often associated with activation delay and therefore might be a marker of the location of the so-called slow pathway. METHODS: The AV junction was scanned for double component action potentials in Langendorff perfused pig and dog hearts, using conventional microelectrode recordings. Characteristics of these action potentials were investigated during basic and premature stimulation and cooling of the anterior approach to the node. RESULTS: During basic stimulation, double component action potentials were recorded in 19 out of 20 hearts. In 74% of these cases, the second component occurred before the His deflection. During premature stimulation this percentage was 50%, while delay between the two components always increased. In 80% of the cases, the amplitude of the two components became <20 mV during progressive shortening of the coupling interval. The first component was generated by activation in superficial layers, the second one by activation in deeper layers. Cooling of the anterior region revealed that the second component was caused by activation arriving from the anterior region. CONCLUSIONS: Double component action potentials in the posterior approach to the AV node are generated by the asynchronous arrival of wave fronts in different, weakly coupled layers or by the summation of asynchronously arriving wave fronts. They are not always associated with activation delay in the slow pathway.  (+info)

The preface of this text indicates that it would be of value as a guide for people starting to perform His bundle electrocardiography and also useful to those established in the field. Unfortunately, it has not reached these goals. Anatomical description has been stretched out over four chapters, but it lacks such pertinent details as the dimensions of the His bundle and bundle branches, and histology of the sinus node, A-V node, and accessory pathways. Chapter four on methodology for recording His bundle electrograms fails to mention the arm approach or the left heart techniques. The methodology used by the ...
The evolution of bilateral bundle branch block (BBB) was studied in ten anesthetized dogs by recording electrical activity from the bundle of His (Hb), right (Rb) and left bundles (Lb) for precise localization and characterization of the conduction disorder. Records were obtained before and at intervals up to 8 hours after ligation of the anterior septal artery. Forty to 140 min after ligation conduction was impaired in either the Rb or Lb showing complete BBB both at rapid heart rates (tachycardia-dependent) and slow rates (bradycardia-dependent) with normal QRS or incomplete BBB at control rates. Later complete BBB became constant at all heart rates. When both bundles were significantly involved, various combinations of intraventricular and atrioventricular conduction disorders occurred. Unequal delay in both bundles (unequal 1° bilateral BBB) gave rise to prolonged H-V interval and a QRS pattern of incomplete or complete bundle branch block corresponding to the branch in which the conduction ...
Procainamide (PA) increases the effective refractory period of the atria, and to a lesser extent the bundle of His-Purkinje system and ventricles of the heart. It reduces impulse conduction velocity in the atria, His-Purkinje fibers, and ventricular muscle, but has variable effects on the atrioventricular (A-V) node, a direct slowing action and a weaker vagolytic effect which may speed A-V conduction slightly. Myocardial excitability is reduced in the atria, Purkinje fibers, papillary muscles, and ventricles by an increase in the threshold for excitation, combined with inhibition of ectopic pacemaker activity by retardation of the slow phase of diastolic depolarization, thus decreasing automaticity especially in ectopic sites. Contractility of the undamaged heart is usually not affected by therapeutic concentrations, although slight reduction of cardiac output may occur, and may be significant in the presence of myocardial damage. Therapeutic levels of PA may exert vagolytic effects and produce ...
This is an example of a normal finding on intracardiac electrophysiologic (EP) study. The surface electrocardiogram (ECG) is represented in different colors, with its corresponding intervals (ie, PR, QT) on top. A catheter with several electrodes is placed inside the heart, close to the superior vena cava-right atrial junction. This catheter records the sinoatrial node (SN) activity and is depicted here as the high-right atrial (HRA) deflection. Beneath the HRA intracardiac electrogram is the His-bundle intracardiac electrogram, which is recorded by the electrodes of a second catheter placed across the posterior aspect of the tricuspid valve. The His-bundle electrogram provides the most information about atrioventricular (AV) conduction. Three main deflections are present, with 2 intervals: (1) the A deflection corresponds to the activation of the low-right atrium, (2) the H deflection corresponds to the activation of the His-bundle before its branching into the Purkinje system, and (3) the V ...
Besides enhanced automaticity, ischemia also provides the substrate for reentry by increasing dispersion of excitability, reducing conduction velocities, and shortening refractory periods in ischemic areas (Coronel, 1994). Occlusion of the LAD resulted in a significant increase in Q-J time. The Q-J time reflects ventricular activation, the time needed for the electrical impulse to travel through the fast-conducting His-Purkinje system to the cardiomyocytes, and to activate the majority of these cells so that their action potential is in phase 2. Regional ischemic injury within the myocardium disturbs intraventricular conduction (Gettes and Cascio, 1992), in both space and time, leading to an altered spectrum of the QRS complex (Hatala et al., 1995) and an increase in Q-J time. The latter is mainly due to the slower or even blocked impulse conduction in the ischemic region. An altered spectrum of the QRS complex and an increase in the Q-J time have been demonstrated in the ischemic control group ...
An example of bilateral bundle-branch block (RBBB) in the presence of WPW syndrome in which diagnosis was established with the aid of His bundle recordings is presented. Complete RBBB and intermittent block of the superior and inferior divisions of the left bundle branch were coexistent for at least 2 years before complete heart block (trifascicular block) occurred. It was demonstrated that the preexcitation pathway conducted and blocked together with the normal pathways. It is suggested that the anomalous bundle in this case traveled with the normal pathways and that this close relationship is more common than has been suspected.. Retrograde V-A conduction at 1:1 ratio was present during electrical stimulation of the right ventricle and the anomalous bundle was used for retrograde spread of activation from the ventricles to the atria. The retrograde P waves, thus produced, conducted antegrade through the His bundle (reciprocation) but reached the ventricles only when they appeared near the end ...
TY - JOUR. T1 - Low-energy transvenous ablation of the canine atrioventricular conduction system with a suction electrode catheter. AU - Saksena, S.. AU - Tarjan, P. P.. AU - Bharati, S.. AU - Boveja, B.. AU - Cohen, D.. AU - Joubert, T.. AU - Lev, M.. PY - 1987/11/4. Y1 - 1987/11/4. N2 - A single suction electrode catheter was used for His bundle electrogram recording, His bundle pacing, and low-energy (20 or 30 J) His bundle ablation in seven dogs. The suction electrode catheter was actively fixed to the atrial endocardium at the His bundle level. Electrophysologic studies were performed in the control state, immediately after, and late (, 40 days) after His bundle ablation and results were correlated with histologic findings in the conduction system. Unipolar His bundle recording and pacing were successfully performed in all dogs with the suction electrode catheter before and after ablation. Complete heart block developed after a single 20 J shock delivered via the suction electrode catheter ...
Under normal physiologic conditions, the dominant pacemaker cells of the heart lie within the sinoatrial node; in adults, these pacemaker cells fire at rates between 60 to 100 beats per minute (i.e., faster than cells in any other cardiac region, See Figure 3). Even at rest, modulation by the autonomic nervous system dominates, with the primary drive from the parasympathetics; at rest or during sleep, the sinoatrial nodal rate decreases to about 75 beats per minute (bpm) or even slower.. In addition to pacemaker cells of the sinoatrial node, other cells within the conduction system are capable of developing autorhythmicity, specifically those within the atrioventricular node (junction region) and His-Purkinje system. Yet, rhythms generated within these cells are in a much lower range (25 to 55 bpm), hence not altering the intrinsic atrial rates (Figure 2). These lower rate rhythms are commonly referred to as ventricular escape rhythms and are important for patient survival, since they maintain ...
Several features remained to be clarified concerning the developmental origin of the atrioventricular conduction axis. For example, is the embryonic atrioventricular canal the major source of the atrial part of the conduction axis,10,11,13 or are major contributions made by adjacent tissues, such as the atrial chamber myocardium, the left sinus horn, the dorsal mesenchymal protrusion, or the atrioventricular bundle?15,17,-,20 What are the lineage origins of the atrial and ventricular parts of the axis, respectively?19,20 By our use of genetic lineage tracing, we have excluded the notion that contributions to the atrial part of the axis are made from the sinus horns or the epicardium (Tbx18+), from the ventricular myocardium, including the atrioventricular bundle, or from the dorsal mesenchymal protrusion (Mef2c-AHF-Cre+). The majority of the atrial components is derived from the embryonic atrioventricular canal, except for the lower nodal cells, which are derived from the embryonic ventricular ...
A form of ventricular pre-excitation characterized by a short PR interval and a normal QRS complex. In this syndrome, the atrial impulse conducts via the JAMES FIBERS which connect the atrium to BUNDLE OF HIS bypassing the upper ATRIOVENTRICULAR NODE. HEART VENTRICLES are depolarized normally through the His-Purkinje system ...
The present study has several limitations. First, electrograms from the region of Kochs triangle were recorded simultaneously only from two atrial sites (i.e., the His bundle recording site and the CS orifice), and simple broad anatomic terms (anterior, middle and posterior) were used to define the anatomic sites of the atrial septum. More detailed endocardial mapping over the triangle of Koch or along the tendon of Todaro (31)may have yielded more information about the exact FP and SP location. However, unlike intraoperative computerized mapping (32), fluoroscopy cannot identify precise endocardial anatomy and, therefore, the presumed FP or SP location has only been inferential, even with the use of decapolar electrode catheters-an inherent limitation to clinical electrophysiologic study. In addition, mapping restricted over the right endocardial surface can only provide limited information about the excitation of the AV node and the atrial septum, which are three-dimensional subendocardial ...
Out-of-hospital cardiac arrest treated by emergency medical services has an estimated incidence of 54.99 per 100,000 person years, which translates to some 155,000 episodes annually in the United States. Bradyasystole is the first recorded rhythm in up to 52 percent of cardiac arrests, and many additional patients with an initial cardiac arrest rhythm of ventricular fibrillation deteriorate to bradyasystole after defibrillation efforts. Survival to hospital discharge occurs in less than 3 percent of patients presenting with bradyasystole; however, due to its frequency, this rhythm accounts for over 17 percent of all cardiac arrest survivors. As a result, even a small improvement in survival from bradyasystolic cardiac arrest would result in thousands of lives saved annually.. Adenosine is an endogenous purine nucleoside that depresses the sinoatrial node, blocks atrioventricular conduction, inhibits the pacemaker activity of the His-Purkinje system and attenuates the effects of catecholamines. ...
Individual compartments of cardiac conduction system (CCS) became functional in order which correlates with cardiac morphogenesis. Ventricular CCS compartments mature with ventricular septation and it is accompanied by shift of activation pattern from primitive base to apex, which follows blood flow
Eleven patients with an accessory pathway and reciprocating tachycardia were studied using both fixed rate atrial pacing and the atrial extrastimulus technique. Six of the patients had an accessory pathway that conducted in both the anterograde and r
The purpose of this study is to explore if there is a less harmful way to pace patients with first-degree AV-block to ensure that the negative effects inferred by the pacing do not outweigh the positive effects of AV-synchrony. The main hypothesis of the study is that His-bundle pacing will offer a more physiological mode of pacing in patients with first-degree AV-block than conventional pacing.. Patients scheduled for catheter ablation of atrial fibrillation (AF) in sinus rhythm, with first degree AV-block, normal QRS duration less than 120 ms and normal left ventricular ejection fraction will be included. During the AF ablation three different pacing modes (atrial, AV-synchronous and His-bundle pacing) at two different rates (5 to10 bpm above the basal rate and at 100 bpm) will be performed and evaluated using echocardiography. After the completion of all six pacing protocols (i.e., three modes at two different rates) the experimental part of the procedure ends.. The primary end-point will be ...
Definisi Hambatan Atrioventrikuler (Atrioventricular block) adalah kelainan pada sistem koduksi jantung dimana depolarisasi atrium gagal untuk mencapai ventrikel atau depoilarisasi atrial yang terkonduksikan dengan terlambat. Hambatan Atrioventrikuler (Blok AV) kerap menjadi penyebab bradikardia meskipun lebih jarang dibandingkan dengan kelainan fungsi nodus SA yang juga menyebabkan gejala bradikardia. 2.2. Klasifikasi Berdasarkan derajat hambatan, gangguan ini dibagi menjadi blok AV derajat 1, blok AV derajat 2, dan blok AV derajat 3 ( total ). Blok AV Derajat 1 terjadi bila semua impuls dari atrium dapat dihantarkan ke ventrikel dengan waktu hantaran yang lebih lama ( pada EKG interval PR, 0,20 detik ). Kelainannya biasanya pada tingkat nodus AV dan jarang pada sistem His-Purkinje. Karena semua impuls dari atrium dapat dihantarkan ke ventrikel maka biasanya tidak menimbulkan gejala. Blok AV Derajat 2 terjadi pada keadaan dimana tidak semua impuls dari atrium dapat dihantarkan melalui nodus AV ...
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Right bundle branch block Differential diagnosis of right bundle branch block / causes of right bundle branch block are : -pulmonary embolism
The cardiac conduction system is a complex network of cells that together orchestrate the rhythmic and coordinated depolarization of the heart. The molecular mechanisms regulating the specification and patterning of cells that form this conductive network are largely unknown. Studies in avian models have suggested that components of the cardiac conduction system arise from progressive recruitment of cardiomyogenic progenitors, potentially influenced by inductive effects from the neighboring coronary vasculature. However, relatively little is known about the process of conduction system development in mammalian species, especially in the mouse, where even the histological identification of the conductive network remains problematic. We have identified a line of transgenic mice where lacZ reporter gene expression delineates the developing and mature murine cardiac conduction system, extending proximally from the sinoatrial node to the distal Purkinje fibers. Optical mapping of cardiac electrical ...
Left bundle branch blocks. In left bundle branch block (LBBB) the left ventricle is not directly activated by impulses travelling through the left bundle branch. The right ventricle, however, is still activated as normal by the right bundle branch.. The left ventricle is activated by impulses travelling through the myocardium across the septum. As this occurs more slowly than conduction through the bundle of His the QRS complex becomes widened.. Normally the septum is activated from left to right, which produces small Q waves in the lateral leads. In the presence of LBBB, however, this septal activation is reversed, which eliminates these normal septal Q waves.. The right to left depolarization of the myocardium produces deep S waves in the right praecordial leads (V1-V3) and tall R waves in the lateral leads (I, V5 and V6). It also usually causes left axis deviation. As the ventricles are activated sequentially from right to left, rather than simultaneously, the R wave in the lateral leads is ...
SCN5A_HUMAN] Defects in SCN5A are a cause of progressive familial heart block type 1A (PFHB1A) [MIM:113900]; also known as Lenegre-Lev disease or progressive cardiac conduction defect (PCCD). PFHB1A is an autosomal dominant cardiac bundle branch disorder that may progress to complete heart block. PFHB1A is characterized by progressive alteration of cardiac conduction through the His-Purkinje system with right or left bundle branch block and widening of QRS complexes, leading to complete atrioventricular block and causing syncope and sudden death.[1] [2] [3] [4] [5] [6] Defects in SCN5A are the cause of long QT syndrome type 3 (LQT3) [MIM:603830]. Long QT syndromes are heart disorders characterized by a prolonged QT interval on the ECG and polymorphic ventricular arrhythmias. They cause syncope and sudden death in response to exercise or emotional stress. LQT3 inheritance is an autosomal dominant.[7] [8] [9] [10] [11] [12] [13] [14] [:][15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] ...
Disease of the CCS is common and can result from congenital abnormalities or can be acquired later in life. As such, a better understanding of the basic biology and molecular pathways underlying cardiac conduction tissue development, maintenance, and function may have significant impact on the clinical care of patients with conduction disorders.. In this report, we show that Hop is highly expressed in the adult CCS of mice and modulates cardiac conduction system function. Hop is a transcriptional target of Nkx2-5, which is also highly expressed in the CCS12 and is required for normal development and maintenance of adult cardiac conduction tissue.4,5 Mutations in Nkx2-5 are associated with proximal conduction system defects in humans and with congenital heart disease.6 Tissue-specific inactivation of Nkx2-5 in adult mouse hearts leads to progressive loss of conduction tissue and downregulation of Hop.4 Our data suggest that Hop is robustly expressed in the adult CCS. However, unlike Nkx2-5, Hop ...
The most common causes of a right bundle branch block are a previous heart attack, a congenital deformity, cardiovascular disease...
Right bundle branch block treatment is not always necessary but it can be essential to ensure the condition doesnt exacerbate. Complication and prevention is also available.
The development and structure of the cardiac conduction system, including the known molecular and cellular factors that regulate development of the conduction system are outlined. Part II includes...
The AV node receives two inputs from the atria: posteriorly via the crista terminalis, and anteriorly via the interatrial septum.[1] An important property that is unique to the AV node is decremental conduction, in which the more frequently the node is stimulated, the slower it conducts. This is the property of the AV node that prevents rapid conduction to the ventricle in cases of rapid atrial rhythms, such as atrial fibrillation or atrial flutter. The atrioventricular node delays impulses for ~0.1 second before allowing impulses through to the His-Purkinje conduction system, which spreads impulses to the ventricular walls. The reason it is important to delay the cardiac impulse is to ensure that the atria have ejected their blood into the ventricles before the ventricles contract.[2] ...
Definition of bundle branch block, complete in the Legal Dictionary - by Free online English dictionary and encyclopedia. What is bundle branch block, complete? Meaning of bundle branch block, complete as a legal term. What does bundle branch block, complete mean in law?
... : An Anatomico-Histological Study of the Atrioventricular Bundle and the Purkinje Fibers (Cardiopulmonary Medicine from I*C*P*, Volume 234) http://s10.postimg.org/ws4yk7trt/The_Conduction_System_of_the_Mammlian_Heart.jpg By Sunao Tawara, Kozo Suma, Munehiro Shimada Hardcover: 256 pages Publisher: WSP Co; 1 edition (September 1, 1998) Language: English ISBN-10: 1860941168 ISBN-13: 978-1860941160
Importance of Retrograde Atrial Activation in Atrial Fibrillation Genesis in the Initiation of Atrial Fibrillation in Wolff-Parkinson-White Syndrome. Comparison of Atrial Electrophysiologic Parameters between Patients with Different Atrial Fibrillation Genesis (Initiation Sites) in Atria. (1999 ...
... -lead ECG Gustav Schellack SASOCP Workshop 10 March 2012 © G Schellack; 2012 Electrocardiogram (ECG)    The ECG is a graphic recording of the electrical activity of the heart, at a specific moment in time. Note: Electrical activity refers to the depolarisation and repolarisation of the atria and ventricles. Note: The ECG cannot tell us anything about the mechanical activity (i.e. contraction and relaxation) of the myocardium. Cardiac Conduction System Anatomical orientation: Figure 1: (Marquette Electronics, 1996) (From: Yanowitz, FG. The Alan E Lindsay ECG Learning Centre in Cyberspace [homepage on the Internet]. c2012. Available from: http://library.med.utah.edu/kw/ecg/index.html.) The Cardiac Impulse Originates from the SA-node (in the RA) Spreads through both atria [virtually] simultaneously RA Spreads through both atria [virtually] simultaneously LA Activates both ventricles via the His-Purkinje network; first the septum from (L) to (R), then the RV, then ...
Dr. Stern responded: None necessary. No treatment necessary and it is not serious unless other |a href="/topics/heart" track_data="{
How do the interpretation rules for ST segment proportionality, concordance and discordance apply to right bundle branch block in patients with chest pain ...
MalaCards based summary : Right Bundle Branch Block, also known as right bundle branch block with left posterior fascicular block, is related to heart block, progressive, type ia and rheumatic heart disease. An important gene associated with Right Bundle Branch Block is SCN5A (Sodium Voltage-Gated Channel Alpha Subunit 5), and among its related pathways/superpathways are Activation of cAMP-Dependent PKA and Developmental Biology. The drugs Tolvaptan and Arginine Vasopressin have been mentioned in the context of this disorder. Affiliated tissues include heart, testes and spinal cord, and related phenotype is cardiovascular system ...
TY - JOUR. T1 - Clinical and genetic heterogeneity of right bundle branch block and ST-segment elevation syndrome. T2 - A prospective evaluation of 52 families. AU - Priori, Silvia G.. AU - Napolitano, Carlo. AU - Gasparini, Maurizio. AU - Pappone, Carlo. AU - Della Bella, Paolo. AU - Brignole, Michele. AU - Giordano, Umberto. AU - Giovannini, Tiziana. AU - Menozzi, Carlo. AU - Bloise, Raffaella. AU - Crotti, Lia. AU - Terreni, Liana. AU - Schwartz, Peter J.. PY - 2000/11/14. Y1 - 2000/11/14. N2 - Background - The ECG pattern of right bundle branch block and ST-segment elevation in leads V1 to V3 (Brugada syndrome) is associated with high risk of sudden death in patients with a normal heart. Current management and prognosis are based on a single study suggesting a high mortality risk within 3 years for symptomatic and asymptomatic patients alike. As a consequence, aggressive management (implantable cardioverter defibrillator) is recommended for both groups. Methods and Results - Sixty patients ...
FLEC : Flecainide (Tambocor) is a class I cardiac antiarrhythmic agent with electrophysiologic properties similar to lidocaine, quinidine, procainamide, and tocainide. Flecainide produces a dose-related decrease in intracardiac conduction in all parts of the heart, with the greatest effect on the His-Purkinje system. Atrial effects are limited. Flecainide causes a dose-related and plasma concentration-related decrease in single and multiple premature ventricular contractions and can suppress recurrence of ventricular tachycardia.   Flecainide is eliminated from blood by hepatic metabolism as well as renal clearance; significant changes in either organ system will cause impaired clearance. During preclinical trials, patients with congestive heart failure were observed to have radically altered clearance properties. Cardiac toxicity attributed to flecainide is related to its cardiac conduction slowing properties. Excessive prolongation of PR, QRS, and QT intervals occurs with increased amplitude
Arrhythmias that originate in the ventricular myocardium or His-Purkinje system include premature ventricular beats, ventricular tachycardias that can be sustained or nonsustained, and ventricular fibrillation. Arrhythmia may emerge from a focus of myocardial or Purkinje cells capable of automaticity, or triggered automaticity, or from reentry through areas of scar or a diseased Purkinje system. Ventricular arrhythmias are often associated with structural heart disease and are an important cause of sudden death (Chap. 327). They also occur in some structurally normal hearts, in which case they are usually benign. Evaluation and management are guided by the risk of arrhythmic death, which is assessed based on symptoms, type of arrhythmia, and associated underlying heart disease. ...
We report the case of a 56-year-old male with ischemic cardiomyopathy, severe left ventricular dysfunction and right bundle branch block (RBBB) with a wide QRS duration (180ms) who received dual-chamber implantable cardioverter-defibrillator for prim
Question - Is right bundle branch block related to kidney problem?. Ask a Doctor about diagnosis, treatment and medication for Arrhythmogenic right ventricular dysplasia, Ask a Cardiac Surgeon
Dear Doctor, I have been diagnost with an incomplete right bundle branch block. I am 45 and 108 punds. All physical, stress test and blood work is fine. The doctor tells me not to worry. However ...
Karel Frederik Wenckebach (March 24, 1864 - November 11, 1940) was a Dutch anatomist who was a native of the Hague. He studied medicine in Utrecht, and in 1901 become a professor of medicine at the University of Groningen. Later he was a professor at the Universities of Strasbourg (1911-14) and Vienna (1914-29). Wenckebach (pronounced ven-kĕ-bak) is primarily remembered for his work in cardiology. In 1899 he provided a description of irregular pulses due to partial blockage of atrioventricular conduction, creating a progressive lengthening of conduction time in cardiac tissue. The condition was referred to as a "second degree AV block" and later named the "Wenckebach phenomenon" and reclassified as Mobitz type I block in Mobitzs 1924 paper. A similar phenomenon can also occur in the Sinoatrial node where it gives rise to Type I second degree SA block, and this is also known as a Wenckebach block; the two have distinct features on an ECG however. Wenckebach is credited for describing the ...
Bundle branches are clusters of pathways that carry electrical impulses to different parts of your heart. A bundle branch block is a delay or obstruction in one of the pathways. These can keep your heart from pumping normally. Many blocks are caused by heart disease, some are there at birth. If the condition is serious, a pacemaker may be prescribed.   The key bundle is the bundle of His, the him in question being the discoverer, Wilhelm His, Jr. This bundle distributes the electrical impulse from the AV node to each ventricle, where it branches into the left and right bundle branches.
Properties of the cardiac muscle AUTOMATICITY CONDUCTIVITY CONTRACTILITY EXCITABILITY REFRACTORY PERIODS 1. AUTOMATICITY is the unique ability of the cells in the SA node (pacemaker cells) to generate an action potential without being stimulated.
The term cardiac preexcitation was originally used to describe premature activation of the ventricles in patients with the Wolff-Parkinson-White (WPW) pattern. This term has been broadened to include all conditions in which antegrade ventricular acti
Aphids ingest their food from sieve tubes (Auclair, 1963; Miles, 1987; Prado and Tjallingii, 1994) that contain a concentrate of nutrients (Hayashi and Chino, 1990; van Bel, 2003). Sieve-tube sap is withdrawn by specialized aphid mouth parts (stylets) (Auclair, 1963; Miyazaki, 1987). Prior to ingestion, aphids secrete watery saliva, probably to interfere with plant occlusion reactions induced by stylet damage (Will and van Bel, 2006; Will et al., 2007; Will et al., 2009; Carolan et al., 2009).. Transmission electron microscopy (TEM) reconstructions demonstrate relatively straightforward stylet progression through the extravascular tissue that occurs largely intercellularly. The stylet orientation becomes increasingly diffuse within the vascular bundle region, as the TEM reconstructions show several dead-end tracks of gel saliva, which is secreted to function as a lubrication and protection sheath for the fragile mouth parts (Tjallingii and Hogen Esch, 1993). Even punctured sieve tubes are ...
Aims We investigated the applicability of the Ventricular Capture Control (VCC) and Atrial Capture Control (ACC) algorithms for automatic management of cardiac stimulation featured by Biotronik pacemakers in a broad, unselected population of pacemaker recipients. Methods and results Ventricular Capture Control and Atrial Capture Control were programmed to work at a maximum adapted output voltage as 4.8 V in consecutive recipients of Biotronik pacemakers. Ambulatory threshold measurements were made 1 and 12 months after pacemaker implant/replacement in all possible pacing/sensing configurations, and were compared with manual measurements. Among 542 patients aged 80 (73-85) years, 382 had a pacemaker implant and 160 a pacemaker replacement. Ventricular Capture Control could work at long term in 97% of patients irrespectively of pacing indication, lead type, and lead service life, performance being superior with discordant pacing/sensing configurations. Atrial Capture Control could work in 93% of ...
Junctional rhythm is an abnormal heart rhythm in the atrioventricular node. Though its not always dangerous, it can be a sign of...
I have RBBB, and occasional PVCs, sometimes during exercise. Should answer 1 say or you have PVCs with right bundle branch block morphology on EKG?? Could you tell me, are there PVCs with a left and right bbb morphology (and which is visible on the EKG?) The first answer scared me a little bit, to be honest.. Sometimes I have a tachycardia which I cannot explain. It starts with me feeling my heart beating in my throat. It feels like my heart has suddenly shifted 20 cm upwards in my chest and I can feel it beat high in my chest / throat. One time this happened before going to the gym. It started to accelerate to about 160 bpm, then I tried to relax and it went back to about 100 bpm. I refused to give in to anxiety, so I started to work out anyway. However, as soon as I started lifting weights (and thus my heartrate would go up) I would immediately feel it back in my throat. It was so annoying (and still scary) that I gave up working out after 10 mins, because it didnt feel good ...
This information is intended for physicians and related personnel, who understand that medical information is often imperfect, and must be interpreted in the context of a patients clinical data using reasonable medical judgment. This website should not be used as a substitute for the advice of a licensed physician ...
DENVER/November 30, 2018 - Morris Animal Foundation-funded researchers have developed a new treatment for dogs with a rare, but life-threatening, arrhythmia caused by atrioventricular accessory ...
Is there a P Wave before each QRS? Are P waves upright and uniform? occur before, during or after the QRS depending on where the pacemaker is located in the AV junction.; P wave may be inverted ...
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The antiarrhythmic, electrophysiologic and hemodynamic effects of a new antiarrhythmic agent, ACC-9358, were evaluated. In anesthetized dogs, ACC-9358 converted ouabain-induced ventricular tachycardia to normal sinus rhythm at a cumulative dose equal to encainide or flecainide and less than disopyramide. In 24-hr coronary artery ligated dogs, ACC-9358 suppressed spontaneous ventricular arrhythmias for up to 6 hr after oral or i.v. administration. The antiarrhythmic effect and plasma concentrations of ACC-9358 correlated well for both oral (r = 0.88) and i.v. (r = 0.87) administration. ACC-9358, flecainide and disopyramide were equieffective in converting crush-stimulation-induced atrial flutter in anesthetized dogs to normal sinus rhythm. In alpha-chloralose-anesthetized, closed-chest dogs, ACC-9358 slowed impulse conduction through the atria, atrioventricular node, His-Purkinje system and ventricles and prolonged atrial functional refractory period. In conscious dogs, ACC-9358 increased heart ...
Looking for online definition of atrioventricular conduction in the Medical Dictionary? atrioventricular conduction explanation free. What is atrioventricular conduction? Meaning of atrioventricular conduction medical term. What does atrioventricular conduction mean?
BioAssay record AID 55773 submitted by ChEMBL: Concentration required for 20% increase in the functional refractory period of canine ventricular muscle (extracellular electrophysiology) in vitro was reported. Range is between 9-4000.
This is a fascinating case, Dr. Smith, and your explication of the essential features is as usual brilliant. Thanks. The patient does seem to also have left atrial enlargement, probably a result of mitral valve disease (stenotic, severely regurgitant, or mixed); this is evidenced by p mitrale - seen in all the limb and augmented limb leads - and the biphasic and terminal negative p wave in V1. There is no evidence of AF in this ECG. Interestingly the PR interval appears a touch short to my eye in some of the leads, especially the lateral precordials. Is that a delta wave in V2? I wonder if the LA enlargement was related to the STEMI. Did he have any visible thrombi in the LA? ReplyDelete ...
A dual chamber pacemaker system is provided having an improved Wenckebach response for optimizing tracking of atrial signals having rates within a rate range above the normal tracking range, i.e., in a designated Wenckebach range. When an atrial sense occurs in the Wenckebach range, the AV delay is extended up to a predetermined maximum extension to enable delivery of a ventricular pulse at the ventricular upper rate limit (dynamic tracking limit). When the AV delay would have to be extended beyond the maximum extension in order to pace the ventricle at the dynamic tracking limit, the next ventricular stimulus is delivered asynchronously at an escape interval greater than the escape interval corresponding to the dynamic tracking limit, e.g., at a predetermined lower pacing limit.
A method and system for ascertaining the condition of the hearts conduction system in a patient treated for congestive heart failure with pacing therapy. In accordance with the invention, changes in ventricular activation patterns are monitored over time in order to detect changes in the hearts conduction system that may occur due to physiological regeneration of conduction pathways. The activation patterns are reflected by electrogram signals detected from different ventricular locations. By measuring the difference in conduction times of an excitation impulse traveling from the AV node to the different ventricular locations, a parameter representative of the hearts conduction system is obtained that may be used to adjust the pacing therapy in accordance therewith.
That is what is happening in this tracing as diagrammed in Figure 2. R3 is conducted from P4. The next P-wave (P5) is blocked because this patient cannot conduct at that R-P interval. The next P-wave (P6) was going to be conducted. How do I know that? This patients AV junction can conduct at 1.4 s as demonstrated by R3. R3-P6 interval is certainly longer than that assuring that P6 would have conducted to the ventricles if it werent for the junctional escape beat (R4); thus, the diagnosis of 2:1 AV block is securely established. This repeats again and again. If, later, a P-wave occurs with a conductible R-P interval which is shorter than AV junctional escape interval (1.6 s in this patient), that P-wave would conduct to the ventricles as P4 did. These junctional escape beats occur close to sinus P-waves during each others refractory period and AV dissociation (not necessarily AV block) results with those beats. ...
A sinus ostium is the opening that connects a sinus to the nasal cavity itself. It is a tight area that tends to have a higher percentage of cilia than the surrounding mucosa. If the sinus ostium is blocked this will cause an accumulation of fluid in the sinus ...
Electrocardiogram on admission depicting 1 mm ST segment elevation in lateral leads with associated right bundle branch block and ventricular beats in couplet
Accelerated junctional rhythm (AJR) occurs when the rate of an AV junctional pacemaker exceeds that of the sinus node. ECG Library LITFL
J:211437 de la Rosa AJ, Dominguez JN, Sedmera D, Sankova B, Hove-Madsen L, Franco D, Aranega AE, Functional suppression of Kcnq1 leads to early sodium channel remodelling and cardiac conduction system dysmorphogenesis. Cardiovasc Res. 2013 Jun 1;98(3):504-14 ...
Methods and systems for classifying cardiac responses to pacing stimulation and/or preventing retrograde cardiac conduction are described. Following delivery of a pacing pulse to an atrium of the patientheart during a cardiac cycle, the system senses in the atrium for a retrograde P-wave. The system classifies the atrial response to the pacing pulse based on detection of the retrograde P-wave. The system may also sense for an atrial evoked response and utilize the atrial evoked response in classifying the cardiac pacing response.
Study of the cardiac conduction system at the macroscopic (layer-preparation, organometry), histological (layered serial histological sections), histochemical, immunohistochemical and ultrastructural ...
An ADI/R mode is implemented using an intelligent pacing system to continually monitor ventricular response. This ensures AV conduction whenever possible so as to gain all the benefits of cardiac contractile properties resulting from native R-waves. In the event where AV conduction is blocked, the pacing mode is switched to a DDD/R mode to ensure a paced R-wave. Thereafter, subsequent to a completed interval of a P-wave, ADI/R pacing resumes to monitor ventricular response.
AV nodal tissue is a not compact structure as we would be believe . But it is a fact , AV node do attempt to compact after birth. It is never complete. All specialised cells should coalesce to form the compact zone .This fails to happen in many . Failure of AV nodal compaction results …
Exploring all aspects of research related to disorders of the heart and circulatory system, BMC Cardiovascular Disorders is a well-established open access ...
Question - What is anteroseptal myocardial infraction ?. Ask a Doctor about diagnosis, treatment and medication for Cardiac arrhythmia, Ask a Cardiologist
About PQRST in ECG, P Wave,Q Wave, Significance of Q Wave in Lead III, Differential Diagnosis of Abnormal Q Wave,R and T waves,ST Segment
DESCRIPTION (provided by applicant): Severe sepsis is a major cause of morbidity and mortality throughout the world. It is the leading cause of death in non-coronary intensive care units (ICUs) in the ... ...
Side 1 av 13 Produktet er ikke klassifisert som farlig og inneholder ingen substans klassifisert som farlig. Derfor er det ingen plikt til å opprette et sikkerhetsdatablad etter REACH artikkel 31 Dette
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இதயம் சீராக சுருங்கி விரிவது இதயத்தின் மின்னோட்ட ஒழுங்கு முறைமையில் தான். இதய மேலறைகள் சுருங்கும் போது கீழறைகள் விரிவடைய வேண்டும். இதயத் துடிப்பு இதயத்தில் SA முடிச்சு எனும் இடத்தில் பிறக்கிறது. இது AV முடிச்சை அடையும் போது அதன் ஓட்டத்தில் சிறிது தாமதம் ஏற்படுத்தப்படுகிறது. இதுவே இதய மேலறைகள் சுருங்கும் போது கீழறைகள் விரிவடைய உதவுகிறது.. இதய அடைப்பை மூன்று நிலைகளாய்ப் ...
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Can left bundle branch block cause chest pain? Mammen Ninan, Jonathan W Swan Exercise-induced left bundle branch block usually indicates underlying coronary artery disease or myocardial disease. Association of left bundle branch block (LBBB) with chest pain in the absence of coronary artery disease is rare. We describe the case history of a patient with chest pain associated with left bundle branch block with normal coronary arteries and review the literature on left bundle branch block associated with chest pain.. ...
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ANSWER: The atrial rate in Figure 1 of this Blog post (at the top of this page) is now faster (~115/minute) than it was when there was 2:1 AV conduction (Note the P-P interval in Figure 1 from Blog Review #19 = 3 large boxes = an atrial rate of 100/minute). Rather than "worsening" of the degree of AV block per se - the lower conduction rate may simply be the result of the faster atrial rate. Treatment of 2nd degree AV block with atropine may at times be a double-edged sword. It may improve the situation (by facilitating conduction through the AV node) - but it can at times worsen the situation by increasing the atrial rate by an amount that may be too fast to conduct. Bottom Line: We suspect that Figure 1 in this Blog post (at the top of this page) represents high-grade 2nd degree AV block, Mobitz Type I - because the QRS is narrow, and Mobitz I is by far the most common form of 2nd degree AV block. Even though treatment with atropine was appropriate (since this drug is often effective for ...
Left Bundle Branch Block Differential diagnosis of left bundle branch block / causes of left bundle branch block are : -ischemic heart disease
Looking for online definition of conduction system in the Medical Dictionary? conduction system explanation free. What is conduction system? Meaning of conduction system medical term. What does conduction system mean?
It was decided that the changes were due to Brugada-like pattern due to Na channel blockaid from flecanide in the setting of recent poor PO intake, nausea and vomiting. Elevated troponin was due to recent ablation. The nausea and vomiting were attributed to dabigatran, which the patient had not tolerated well in the past (she had previously had such GI symptoms). The patient was admitted to telemetry, her Na was replaced with IV fluids, flecainide was discontinued. Metoprolol was started, dabigatran discontinued, and rivaroxaban was started. ECG returned to baseline - incomplete RBBB was still present. Serial troponins remained stable at a low but elevated level. The patient had an uneventful hospital stay. ...
Despite remarkable progress in the past few years, the gene regulatory networks underlying formation and function of the cardiac conduction system (CCS) remain incompletely understood. Transcription factors such as NXK2.5 and TBX2/3/5 that control various aspects of heart development have emerged as key regulators of cardiac conduction gene expression and function. By showing alterations in the structure of the atrioventricular node (AVN) and the electrophysiological parameters of mice harboring a mutated GATA-binding factor 6 (GATA6) protein, Liu et al1 add a new player to the growing list of transcription factors involved in cardiac rhythm regulation. This finding provides insight that will help advance efforts to elucidate the pathogenesis of cardiac rhythm disturbances.. Article see p 284. In human, cardiac rhythm disturbances are a major cause of mortality and morbidity from fetal to adult life. They can develop in response to numerous conditions, such as electrolyte imbalance, ...
Many cardiac excitation problems can be diagnosed from the information in a single lead of an electrocardiogram. The lead II electrocardiogram traces at the top of Figure 5-1 and 5-2 are identified as normal sinus rhythms based on the following characteristics: (1) the frequency of QRS complexes is approximately 1 per second, indicating a normal beating rate; (2) the shape of the QRS complex is normal for lead II and its duration is less than 120 ms, indicating rapid depolarization of the ventricles via normal conduction pathways; (3) each QRS complex is preceded by a P wave of proper configuration, indicating sinoatrial (SA) nodal origin of the excitation; (4) the PR interval is less than 200 ms, indicating proper conduction delay of the impulse propagation through the atrioventricular (AV) node; (5) the QT interval is less than half of the R-to-R interval, indicating normal ventricular repolarization; and (6) there are no extra P waves, indicating that no AV nodal conduction block is present. ...
I am a 48 year old woman who just had an ECG done that showed Left Bundle Branch Block. I think the doctor ordered the ECG to ease my mind because of what I went to see him for really had nothing to d...
Found out last year I have left bundle branch block,worked out I am running a minute a mile slower than normal,has anybody else experienced this or know anything about it?
Why the qrs complex becomes wide and tall in LBBB ? The qrs complex is wide , due to delayed conduction over non specialized fibres .The qrs becomes are tall due to temporal dissociation of RV and LV forces , which leaves the LV forces unopposed , thus a tall qrs is inscribed , without…
Reading a recent medical report I noted the following:"bifascicular block", sinus bradycardia", Right bundle branch block", this after an EKG last week for short period of pain in the middle of the chest. (I feel OK now, swam slowly for 30 minutes this morning (3 times a week for the last several years - and feel better afterward - - but if I dig some dirt in the yard for planting holes of tomatoes or other plants - I can become exhausted quickly (while swimming 30 minutes slowly does not tire me) - I dont know what physical limits I should place on my self? I take atenolol, losaran, 1/2 pill hydroc.thiszd, and hytrin. I generally feel OK everyday. DOB 8/27/33. Thank you very much for any advise or suggestions. Chris ...
A biological amplifier system is disclosed for displaying the cardiac conduction system activity, particularly the His bundle activity on a beat-to-beat basis by a non-invasive technique. Plural sets
A managed ventricular pacing (MVP) algorithm was applied, with the pacemaker working correctly (correct answer, 4). In the upper trace of the Figure, sequential pacing can be observed with an atrioventricular interval of 150 ms, except for the last beat, in which the pacemaker switches to AAI mode. The MPV algorithm periodically makes such checks.1 In the lower trace, the pacemaker is working in AAI mode with atrial pacing (asterisks) when the heart rate drops below the threshold (60 bpm). An atrial pace is present after the sixth QRS: the MVP algorithm will ensure that there is no atrioventricular conduction, but in the next complex (double arrow), the pacemaker emits a safety pace, which with this model has an atrioventricular interval of 80 ms. This is not ventricular capture failure (answers 1 and 2, incorrect) because there is no ventricular pace spike and at no point is failure of atrial capture observed (answer 3, incorrect).. ...
... - Complete atrioventricular block during renal transplantation in a patient with . que desenvolveu bloqueio atrioventricular total durante um transplante
During a complete bundle branch block, many ectopic pacemakers in the ventricles may take over the action of the SA node. The EKG may show which of the following ...
During a complete bundle branch block, many ectopic pacemakers in the ventricles may take over the action of the SA node. The EKG may show which of the following ...
For higher data rate transmission in the area of multiple megabit per seconds CODICOs products according HomePlug AV Standard, come to mind.
Electroanatomically estimated length of slow pathway in atrioventricular nodal reentrant tachycardia. . Biblioteca virtual para leer y descargar libros, documentos, trabajos y tesis universitarias en PDF. Material universiario, documentación y tareas realizadas por universitarios en nuestra biblioteca. Para descargar gratis y para leer online.
Transient complete heart block - What is complete heart block? Heart block. Third-degree atrioventricular block or complete heart block, is a disorder of the cardiac conduction system where there is no conduction through the atrioventricular node. Therefore, complete dissociation of the atrial and ventricular activity exists. It results from various pathologic states causing infiltration, fibrosis, or loss of connection in portions of the healthy conduction system.
The cause of the electrocardiographic abnormalities in amyloidosis is a matter of controversy despite attempts of clinicopathological correlation. Detailed correlative studies of the involvement of cardiac conduction system in amyloidosis are few and have produced conflicting results. Some authors favour the hypothesis that infiltration of the conducting system by amyloid deposits is the main reason for the disturbances of conduction [19]. In familial amyloidosis with polyneuropathy, amyloid infiltration of the sinus node and atrioventricular conduction system is now well documented, and this seems to account for the majority of the electrophysiological disturbances of these regions [20, 21, 22].The distribution and extent of heart infiltration by amyloid are not, however, uniform. On the other hand, other authors have concluded that direct infiltration by amyloid is of lesser importance [14]. Autonomous neuropathy due to amyloid may also contribute to the electrophysiological disturbances. In ...
Looking for atrioventricular (AV) junctional rhythm? Find out information about atrioventricular (AV) junctional rhythm. the basic temporal element of music, concerned with duration and with stresses or accents whether irregular or organized into regular patternings. Explanation of atrioventricular (AV) junctional rhythm
Using bundles in health care[edit]. Using bundles in health care simplifies the complex processes of the care of patients with ... A bundle is a selected set of elements of care distilled from evidence-based practice guidelines that, when implemented as a ... The 24-hour SSC Management Bundle includes: *Low-dose steroids administered for septic shock in accordance with a standardized ... Each hospital's sepsis protocol may be customized, but it must meet the standards created by the bundle. ...
A line bundle, such as the tangent bundle of S1 is trivial if and only if there is a section that vanishes nowhere, see ... the trivial bundle X × V). For example, the Möbius strip can be seen as a line bundle over the circle S1 (by identifying open ... to the trivial bundle U × V → U. Despite their locally trivial character, vector bundles may (depending on the shape of the ... The case dim V = 1 is called a line bundle. For any vector space V, the projection X × V → X makes the product X × V into a " ...
Home Bundle Edition[edit]. National Instruments provides a low cost LabVIEW Home Bundle Edition.[9] ... "LabVIEW Home Bundle for Windows - National Instruments". sine.ni.com. Archived from the original on 2016-07-04.. ...
Service bundling[edit]. For residential users, IPTV is often provided in conjunction with video on demand and may be bundled ... Commercial bundling of IPTV, VoIP and Internet access is sometimes referred to in marketing as triple play service. When these ...
Remak bundles[edit]. C fiber axons are grouped together into what is known as Remak bundles.[3] These occur when a non- ... The condition of Remak bundles varies with age.[4] The number of C fiber axons in each Remak bundle varies with location.[3] ... Remak bundles in the distal peripheral nerve are clustered with other Remak bundles.[3] The Remak Schwann cells have been shown ... Multiple neurons contribute axons to the Remak bundle with an average ratio of about 2 axons contributed per bundle.[3] The ...
See also: Wikipedia:Citing sources § Bundling citations. Template {{harvnb}}. can be used to bundle citations. {{sfnm}}. also ... is inappropriate for bundled citations; use {{harvnb}}. or {{sfnm}}. . More exotic Harvard citations {{harvid}}. or {{harvs}}. ...
Bundled and/or integrated software[edit]. *Microsoft Chat 2.0 is a simple text chatting program included in the Windows NT-line ... It was bundled with Internet Explorer 4, but was also available for free, and could be downloaded from online repositories.[17] ... At the same event, Apple announced the release of Mac OS 8.1, which would be bundled with IE4. ...
... holds that the self cannot be reduced to a bundle because the concept of a self is incompatible with the idea of a bundle. ... Bundle theory of the self[edit]. A Treatise Of Human Nature: Being An Attempt To Introduce The Experimental Method Of Reasoning ... James Giles, a principal exponent of this view, argues that the no-self or eliminativist theory and the bundle or reductionist ... When we start introspecting, "we are never intimately conscious of anything but a particular perception; man is a bundle or ...
There are several types of bundles: pure bundles where the goods can only be purchased as package or mixed bundles where the ... Price bundling (also known as product bundling) occurs where two or more products or services are priced as a package with a ... These include price skimming, price discrimination and yield management, price points, psychological pricing, bundle pricing, ... The prices of the bundle is typically less than when the two items are purchased separately.[24] ...
Bundle from Middle Dutch bondel or perhaps a merger of this word and Old English byndele (binding) [37]. Bung from Middle Dutch ...
... passes through the atrioventricular node down into the bundle of His and into the Purkinje fibers, spreading down and to the ... such as a bundle branch block that alters the shape of the QRS complexes. ECGs can be interpreted in isolation but should be ...
"Bundle of Ivory". January 7, 2003 (2003-01-07). 16. "Ivory Returns". January 8, 2003 (2003-01-08). ...
Bundle, M.W; Dial, K.P. (2003). "Mechanics of wing-assisted incline running (WAIR)" (PDF). The Journal of Experimental Biology ...
Wolinetz, Geoff (June 24, 2010). "Brain Pickings blogger Maria Popova: 'I'm not a big believer in saving'". Bundle. Archived ...
Bundled citation: {{harvnb}}. or {{sfnm}}. [ویرایش]. نوشتار(های) وابسته: Wikipedia:Citing sources § Bundling citations ... is inappropriate for bundled citations; use {{harvnb}}. or {{sfnm}}. . More exotic Harvard citations {{harvid}}. or {{harvs}}. ...
Usually the deep purple roots of beetroot are eaten boiled, roasted or raw, and either alone or combined with any salad vegetable. A large proportion of the commercial production is processed into boiled and sterilized beets or into pickles. In Eastern Europe, beet soup, such as borscht, is a popular dish. In Indian cuisine, chopped, cooked, spiced beet is a common side dish. Yellow-coloured beetroots are grown on a very small scale for home consumption.[9]. The green, leafy portion of the beet is also edible. The young leaves can be added raw to salads, whilst the adult leaves are most commonly served boiled or steamed, in which case they have a taste and texture similar to spinach. Those greens selected should be from bulbs that are unmarked, instead of those with overly limp leaves or wrinkled skins, both of which are signs of dehydration. The domestication of beets can be traced to the emergence of an allele which enables biennial harvesting of leaves and taproot.[10]. Beetroot can be boiled ...
"Full Lima Bundle Released". lpmuds.net. 2009-01-24. Retrieved 2010-05-17.. ...
"Avicii Sets Mark; A Bundle of Brit." Billboard 21 December 2013: 181. ProQuest. Web. 5 October 2015 ...
Shortly after the iPhone 4 was launched, some consumers reported that signal strength of the phone was reduced when touching the lower left edge of the phone, bridging one of the two locations which separates the two antennas, resulting in dropped calls in some areas with lower signal reception.[85][86][87] In response, Apple issued a statement advising that customers should "avoid gripping [the phone] in the lower left corner" when making or receiving a call.[88] As a consequence of this problem, it was reported on July 2, 2010 that several iPhone 4 users were planning on suing Apple and AT&T for fraud by concealment, negligence, intentional misrepresentation and defective design. The legal challenge was started by a law firm, who set up a website to recruit disenchanted iPhone 4 buyers for a lawsuit against Apple.[89][90] Later that day, Apple issued another statement stating that it had discovered the cause of the "dramatic drop in bars".[91] Apple explained how the formula it used to ...
The CAUTI Bundle is similar to the bundles for prevention and treatment of ventilator-associated pneumonia, sepsis, and central ... "Safeek UTI Bundle" (PDF). American College of Physician Executives. Retrieved 2010-04-01. Safeek, Yisrael. "UTI Bundle". ... Safeek published a simple, easy-to-remember urinary tract infections open source bundle (CAUTI Bundle) in Physician Executive, ... The CAUTI Bundle was later reprinted by Healthcare Financial Management Journal upon request as a tool to decrease unnecessary ...
Bundle review. Rumbler, Bill (March 28, 1993). "YOUR 2 CENTS WORTH". Chicago Sun-Times. Retrieved 16 November 2013. ...
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"Life in Bunker features". Humble Bundle. Retrieved 24 April 2016. Markley, John (1 March 2016). "Life In Bunker Review - Deep ...
I have been diagnost with an incomplete right bundle branch block. I am 45 and 108 punds. All physical, stress test and blood ... I have been diagnost with an incomplete right bundle branch block. I am 45 and 108 punds. All physical, stress test and blood ...
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The vascular bundle consists of xylem, which conducts water and dissolved mineral ... vascular bundle vascular bundle. vascular bundle, in botany, a strand of conducting tissue extending lengthwise through the ... The structure of vascular bundles varies among the different plant groups. See wood . The Columbia Electronic Encyclopedia, 6th ... The vascular bundle consists of xylem, which conducts water and dissolved mineral substances from the soil to the leaves, and ...
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His bundle electrography is a test that measures electrical activity in a part of the heart that carries the signals that ... His bundle electrogram; HBE; His bundle recording; Electrogram - His bundle; Arrhythmia - His; Heart block - His ... The bundle of His is a group of fibers that carry electrical impulses through the center of the heart. If these signals are ... His bundle electrography is a test that measures electrical activity in a part of the heart that carries the signals that ...
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... known as the bundle of His) running along the muscular partition between the left and right chambers of the heart. He found ... Other articles where Bundle of His is discussed: Wilhelm His: …muscle fibres ( ... to the atrioventricular node and bundle of His (known as the atrioventricular junctional tissue), through the bundle branches ... Alternative Title: atrioventricular bundle. Learn about this topic in these articles:. discovery by His. * In Wilhelm His. … ...
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bundle branch is a part of the electrical pathway of the heart that delivers electrical impulses to the ventricles of the heart ... What is the definition of bundle branch?. ANSWER Bundle branch is a part of the electrical pathway of the heart that delivers ...
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  • Thus, the set of the isomorphism classes of all line bundles on some topological space X forms an abelian group called the Picard group of X. One can also define a symmetric power and an exterior power of a vector bundle in a similar way. (wikipedia.org)
  • Each video in this series, Patient-Centered Rounds Using the ABCDEF Bundle, shows examples of patient care rounds. (youtube.com)
  • PlanetMath page of universal bundle examples J. J. Duistermaat and J. A. Kolk,-- Lie Groups, Universitext, Springer. (wikipedia.org)
  • Other examples of four-helix bundles include cytochrome, ferritin, human growth hormone, cytokine, and Lac repressor C-terminal. (wikipedia.org)
  • Examples of bundles that contain executable code include applications, frameworks, and plugins. (wikipedia.org)
  • Examples of bundles that do not contain executable code include document packages (iWork documents) and media libraries (iPhoto Library). (wikipedia.org)
  • Community land trusts and land banking are examples of efforts to rearrange the bundle of rights. (wikipedia.org)
  • While many well-known examples of bundling are all products or services from the same store or provider, such as the sports package for a car or a grocery store's gift basket, in some cases, cross-industry bundles are assembled and sold. (wikipedia.org)
  • The Frank Zappa AAAFNRAA Birthday Bundle was released as a digital download on iTunes on December 15, 2006. (wikipedia.org)
  • It is the second iTunes album by Frank Zappa, the first being The Frank Zappa AAAFNRAA Birthday Bundle (2006). (wikipedia.org)
  • If E is a real vector bundle of rank n, then a choice of metric on E amounts to a reduction of the structure group to the orthogonal group O(n). (wikipedia.org)
  • Classifying space for U(n) Chern class tautological bundle, a universal bundle for the general linear group. (wikipedia.org)
  • Because of this, the tautological bundle is important in the study of characteristic classes. (wikipedia.org)
  • All that can stop the definition of the tautological bundle from this indication, is the (pedantic) difficulty that the Vg are going to intersect. (wikipedia.org)
  • By convention and use P(V) may usefully carry the tautological bundle in the dual space sense. (wikipedia.org)
  • We define the tautological bundle γn, k over Gn(Rn+k) as follows. (wikipedia.org)
  • Taking the direct limit of the bundles γn, k gives the tautological bundle γn of Gn. (wikipedia.org)
  • sr] which gives a map from X to Pr, and the pullback of the dual of the tautological bundle under this map is L. In this way, projective space acquires a universal property. (wikipedia.org)
  • Conduction down the left bundle branch proceeds normally, and the interventricular septum and left ventricle rapidly depolarize in the normal fashion. (medscape.com)
  • The left bundle branch further divides into the left anterior fascicles and the left posterior fascicles. (wikipedia.org)
  • Other sources divide the left bundle branch into three fascicles: the left anterior, the left posterior, and the left septal fascicle. (wikipedia.org)
  • In this case only the anterior half of the left bundle branch (fascicle) is involved Left posterior fascicular block. (wikipedia.org)
  • The left ventricle however, is still normally activated by the left bundle branch. (wikipedia.org)
  • There are also partial blocks of the left bundle branch: "left anterior fascicular block" (LAFB) and a "left posterior fascicular block" (LPFB). (wikipedia.org)
  • This refers to the bifurcation of the left bundle branch. (wikipedia.org)