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.Rauwolfia: A plant genus of the APOCYNACEAE or dogbane family. Alkaloids from plants in this genus have been used as tranquilizers and antihypertensive agents. RESERPINE is derived from R. serpentina.Brugada Syndrome: An autosomal dominant defect of cardiac conduction that is characterized by an abnormal ST-segment in leads V1-V3 on the ELECTROCARDIOGRAM resembling a right BUNDLE-BRANCH BLOCK; high risk of VENTRICULAR TACHYCARDIA; or VENTRICULAR FIBRILLATION; SYNCOPAL EPISODE; and possible sudden death. This syndrome is linked to mutations of gene encoding the cardiac SODIUM CHANNEL alpha subunit.Secologanin Tryptamine Alkaloids: Compounds formed by condensation of secologanin with tryptamine resulting in a tetrahydro-beta-carboline which is processed further to a number of bioactive compounds. These are especially found in plants of the APOCYNACEAE; LOGANIACEAE; and RUBIACEAE families.Anti-Arrhythmia Agents: Agents used for the treatment or prevention of cardiac arrhythmias. They may affect the polarization-repolarization phase of the action potential, its excitability or refractoriness, or impulse conduction or membrane responsiveness within cardiac fibers. Anti-arrhythmia agents are often classed into four main groups according to their mechanism of action: sodium channel blockade, beta-adrenergic blockade, repolarization prolongation, or calcium channel blockade.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.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.Fonofos: An organothiophosphorus cholinesterase inhibitor that is used as an insecticide.Chemical Industry: The aggregate enterprise of manufacturing and technically producing chemicals. (From Random House Unabridged Dictionary, 2d ed)Environmental Pollutants: Substances or energies, for example heat or light, which when introduced into the air, water, or land threaten life or health of individuals or ECOSYSTEMS.Occupational Exposure: The exposure to potentially harmful chemical, physical, or biological agents that occurs as a result of one's occupation.Directories as Topic: Lists of persons or organizations, systematically arranged, usually in alphabetic or classed order, giving address, affiliations, etc., for individuals, and giving address, officers, functions, and similar data for organizations. (ALA Glossary of Library and Information Science, 1983)Phytochemicals: A broad range of biologically active compounds which occur naturally in plants having important medicinal and nutritional properties.Manufactured Materials: Substances and materials manufactured for use in various technologies and industries and for domestic use.Industry: Any enterprise centered on the processing, assembly, production, or marketing of a line of products, services, commodities, or merchandise, in a particular field often named after its principal product. Examples include the automobile, fishing, music, publishing, insurance, and textile industries.Industrial Oils: Oils which are used in industrial or commercial applications.Organic Chemicals: A broad class of substances containing carbon and its derivatives. Many of these chemicals will frequently contain hydrogen with or without oxygen, nitrogen, sulfur, phosphorus, and other elements. They exist in either carbon chain or carbon ring form.Particle Size: Relating to the size of solids.Volatile Organic Compounds: Organic compounds that have a relatively high VAPOR PRESSURE at room temperature.Chemistry, Organic: The study of the structure, preparation, properties, and reactions of carbon compounds. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Water Pollutants, Chemical: Chemical compounds which pollute the water of rivers, streams, lakes, the sea, reservoirs, or other bodies of water.Cosmic Dust: Finely divided solid matter with particle sizes smaller than a micrometeorite, thus with diameters much smaller than a millimeter, moving in interplanetary space. (NASA Thesaurus, 1994)Meteoroids: Any solid objects moving in interplanetary space that are smaller than a planet or asteroid but larger than a molecule. Meteorites are any meteoroid that has fallen to a planetary surface. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Domperidone: A specific blocker of dopamine receptors. It speeds gastrointestinal peristalsis, causes prolactin release, and is used as antiemetic and tool in the study of dopaminergic mechanisms.Galactogogues: Substances that induce LACTATION.Gastrointestinal Motility: The motor activity of the GASTROINTESTINAL TRACT.Encyclopedias as Topic: Works containing information articles on subjects in every field of knowledge, usually arranged in alphabetical order, or a similar work limited to a special field or subject. (From The ALA Glossary of Library and Information Science, 1983)Gastroesophageal Reflux: Retrograde flow of gastric juice (GASTRIC ACID) and/or duodenal contents (BILE ACIDS; PANCREATIC JUICE) into the distal ESOPHAGUS, commonly due to incompetence of the LOWER ESOPHAGEAL SPHINCTER.Suppositories: Medicated dosage forms that are designed to be inserted into the rectal, vaginal, or urethral orifice of the body for absorption. Generally, the active ingredients are packaged in dosage forms containing fatty bases such as cocoa butter, hydrogenated oil, or glycerogelatin that are solid at room temperature but melt or dissolve at body temperature.Gastrointestinal Diseases: Diseases in any segment of the GASTROINTESTINAL TRACT from ESOPHAGUS to RECTUM.Drug Information Services: Services providing pharmaceutic and therapeutic drug information and consultation.Pamphlets: Printed publications usually having a format with no binding and no cover and having fewer than some set number of pages. They are often devoted to a single subject.Drug Labeling: Use of written, printed, or graphic materials upon or accompanying a drug container or wrapper. It includes contents, indications, effects, dosages, routes, methods, frequency and duration of administration, warnings, hazards, contraindications, side effects, precautions, and other relevant information.Patient Education as Topic: The teaching or training of patients concerning their own health needs.Formularies as Topic: Works about lists of drugs or collections of recipes, formulas, and prescriptions for the compounding of medicinal preparations. Formularies differ from PHARMACOPOEIAS in that they are less complete, lacking full descriptions of the drugs, their formulations, analytic composition, chemical properties, etc. In hospitals, formularies list all drugs commonly stocked in the hospital pharmacy.Drug Industry: That segment of commercial enterprise devoted to the design, development, and manufacture of chemical products for use in the diagnosis and treatment of disease, disability, or other dysfunction, or to improve function.Medical Records Systems, Computerized: Computer-based systems for input, storage, display, retrieval, and printing of information contained in a patient's medical record.Facial Muscles: Muscles of facial expression or mimetic muscles that include the numerous muscles supplied by the facial nerve that are attached to and move the skin of the face. (From Stedman, 25th ed)Diplopia: A visual symptom in which a single object is perceived by the visual cortex as two objects rather than one. Disorders associated with this condition include REFRACTIVE ERRORS; STRABISMUS; OCULOMOTOR NERVE DISEASES; TROCHLEAR NERVE DISEASES; ABDUCENS NERVE DISEASES; and diseases of the BRAIN STEM and OCCIPITAL LOBE.Migraine Disorders: A class of disabling primary headache disorders, characterized by recurrent unilateral pulsatile headaches. The two major subtypes are common migraine (without aura) and classic migraine (with aura or neurological symptoms). (International Classification of Headache Disorders, 2nd ed. Cephalalgia 2004: suppl 1)Tryptamines: Decarboxylated monoamine derivatives of TRYPTOPHAN.Chest Pain: Pressure, burning, or numbness in the chest.Jaw: Bony structure of the mouth that holds the teeth. It consists of the MANDIBLE and the MAXILLA.Universal Precautions: Prudent standard preventive measures to be taken by professional and other health personnel in contact with persons afflicted with a communicable disease, to avoid contracting the disease by contagion or infection. Precautions are especially applicable in the diagnosis and care of AIDS patients.Echocardiography, Three-Dimensional: Echocardiography amplified by the addition of depth to the conventional two-dimensional ECHOCARDIOGRAPHY visualizing only the length and width of the heart. Three-dimensional ultrasound imaging was first described in 1961 but its application to echocardiography did not take place until 1974. (Mayo Clin Proc 1993;68:221-40)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.Echocardiography: Ultrasonic recording of the size, motion, and composition of the heart and surrounding tissues. The standard approach is transthoracic.Magnetic Resonance Imaging: Non-invasive method of demonstrating internal anatomy based on the principle that atomic nuclei in a strong magnetic field absorb pulses of radiofrequency energy and emit them as radiowaves which can be reconstructed into computerized images. The concept includes proton spin tomographic techniques.Hemodynamics: The movement and the forces involved in the movement of the blood through the CARDIOVASCULAR SYSTEM.Syncope: A transient loss of consciousness and postural tone caused by diminished blood flow to the brain (i.e., BRAIN ISCHEMIA). Presyncope refers to the sensation of lightheadedness and loss of strength that precedes a syncopal event or accompanies an incomplete syncope. (From Adams et al., Principles of Neurology, 6th ed, pp367-9)Carotid Sinus: The dilated portion of the common carotid artery at its bifurcation into external and internal carotids. It contains baroreceptors which, when stimulated, cause slowing of the heart, vasodilatation, and a fall in blood pressure.Electrocardiography, Ambulatory: Method in which prolonged electrocardiographic recordings are made on a portable tape recorder (Holter-type system) or solid-state device ("real-time" system), while the patient undergoes normal daily activities. It is useful in the diagnosis and management of intermittent cardiac arrhythmias and transient myocardial ischemia.Massage: The systematic and methodical manipulations of body tissues best performed with the hands for the purpose of affecting the nervous and muscular systems and the general circulation.Syncope, Vasovagal: Loss of consciousness due to a reduction in blood pressure that is associated with an increase in vagal tone and peripheral vasodilation.Tilt-Table Test: A standard and widely accepted diagnostic test used to identify patients who have a vasodepressive and/or cardioinhibitory response as a cause of syncope. (From Braunwald, Heart Disease, 7th ed)