Accelerated Idioventricular Rhythm: A type of automatic, not reentrant, ectopic ventricular rhythm with episodes lasting from a few seconds to a minute which usually occurs in patients with acute myocardial infarction or with DIGITALIS toxicity. The ventricular rate is faster than normal but slower than tachycardia, with an upper limit of 100 -120 beats per minute. Suppressive therapy is rarely necessary.Cardiac Complexes, Premature: A group of cardiac arrhythmias in which the cardiac contractions are not initiated at the SINOATRIAL NODE. They include both atrial and ventricular premature beats, and are also known as extra or ectopic heartbeats. Their frequency is increased in heart diseases.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.Arrhythmias, Cardiac: Any disturbances of the normal rhythmic beating of the heart or MYOCARDIAL CONTRACTION. Cardiac arrhythmias can be classified by the abnormalities in HEART RATE, disorders of electrical impulse generation, or impulse conduction.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.Chlorpheniramine: A histamine H1 antagonist used in allergic reactions, hay fever, rhinitis, urticaria, and asthma. It has also been used in veterinary applications. One of the most widely used of the classical antihistaminics, it generally causes less drowsiness and sedation than PROMETHAZINE.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.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.Methylhistamines: Histamine substituted in any position with one or more methyl groups. Many of these are agonists for the H1, H2, or both histamine receptors.Heart Rate: The number of times the HEART VENTRICLES contract per unit of time, usually per minute.Circadian Rhythm: The regular recurrence, in cycles of about 24 hours, of biological processes or activities, such as sensitivity to drugs and stimuli, hormone secretion, sleeping, and feeding.Myocardial Infarction: NECROSIS of the MYOCARDIUM caused by an obstruction of the blood supply to the heart (CORONARY CIRCULATION).Nurses: Professionals qualified by graduation from an accredited school of nursing and by passage of a national licensing examination to practice nursing. They provide services to patients requiring assistance in recovering or maintaining their physical or mental health.Hospice Care: Specialized health care, supportive in nature, provided to a dying person. A holistic approach is often taken, providing patients and their families with legal, financial, emotional, or spiritual counseling in addition to meeting patients' immediate physical needs. Care may be provided in the home, in the hospital, in specialized facilities (HOSPICES), or in specially designated areas of long-term care facilities. The concept also includes bereavement care for the family. (From Dictionary of Health Services Management, 2d ed)Hospices: Facilities or services which are especially devoted to providing palliative and supportive care to the patient with a terminal illness and to the patient's family.BooksBook SelectionBook Reviews as Topic: Critical analyses of books or other monographic works.Rare BooksBook PricesBooks, Illustrated: Books containing photographs, prints, drawings, portraits, plates, diagrams, facsimiles, maps, tables, or other representations or systematic arrangement of data designed to elucidate or decorate its contents. (From The ALA Glossary of Library and Information Science, 1983, p114)Reference Books, Medical: Books in the field of medicine intended primarily for consultation.Procainamide: A class Ia antiarrhythmic drug that is structurally-related to PROCAINE.Action Potentials: Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.Electric Countershock: An electrical current applied to the HEART to terminate a disturbance of its rhythm, ARRHYTHMIAS, CARDIAC. (Stedman, 25th ed)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.Atrial Fibrillation: Abnormal cardiac rhythm that is characterized by rapid, uncoordinated firing of electrical impulses in the upper chambers of the heart (HEART ATRIA). In such case, blood cannot be effectively pumped into the lower chambers of the heart (HEART VENTRICLES). It is caused by abnormal impulse generation.Acecainide: A major metabolite of PROCAINAMIDE. Its anti-arrhythmic action may cause cardiac toxicity in kidney failure.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.Heart Failure: A heterogeneous condition in which the heart is unable to pump out sufficient blood to meet the metabolic need of the body. Heart failure can be caused by structural defects, functional abnormalities (VENTRICULAR DYSFUNCTION), or a sudden overload beyond its capacity. Chronic heart failure is more common than acute heart failure which results from sudden insult to cardiac function, such as MYOCARDIAL INFARCTION.Etiocholanolone: The 5-beta-reduced isomer of ANDROSTERONE. Etiocholanolone is a major metabolite of TESTOSTERONE and ANDROSTENEDIONE in many mammalian species including humans. It is excreted in the URINE.Syndrome: A characteristic symptom complex.Health Knowledge, Attitudes, Practice: Knowledge, attitudes, and associated behaviors which pertain to health-related topics such as PATHOLOGIC PROCESSES or diseases, their prevention, and treatment. This term refers to non-health workers and health workers (HEALTH PERSONNEL).Heart Rupture, Post-Infarction: Laceration or tearing of cardiac tissues appearing after MYOCARDIAL INFARCTION.Sodium Potassium Chloride Symporter Inhibitors: Agents that inhibit SODIUM-POTASSIUM-CHLORIDE SYMPORTERS which are concentrated in the thick ascending limb at the junction of the LOOP OF HENLE and KIDNEY TUBULES, DISTAL. They act as DIURETICS. Excess use is associated with HYPOKALEMIA and HYPERGLYCEMIA.Acute Disease: Disease having a short and relatively severe course.Commotio Cordis: A sudden CARDIAC ARRHYTHMIA (e.g., VENTRICULAR FIBRILLATION) caused by a blunt, non-penetrating impact to the precordial region of chest wall. Commotio cordis often results in sudden death without prompt cardiopulmonary defibrillation.Death, Sudden: The abrupt cessation of all vital bodily functions, manifested by the permanent loss of total cerebral, respiratory, and cardiovascular functions.Baseball: A competitive nine-member team sport including softball.Thoracic Injuries: General or unspecified injuries to the chest area.Thoracic Wall: The outer margins of the thorax containing SKIN, deep FASCIA; THORACIC VERTEBRAE; RIBS; STERNUM; and MUSCLES.Ventricular Fibrillation: A potentially lethal cardiac arrhythmia that is characterized by uncoordinated extremely rapid firing of electrical impulses (400-600/min) in HEART VENTRICLES. Such asynchronous ventricular quivering or fibrillation prevents any effective cardiac output and results in unconsciousness (SYNCOPE). It is one of the major electrocardiographic patterns seen with CARDIAC ARREST.Ectopia Cordis: A rare developmental defect in which the heart is abnormally located partially or totally outside the THORAX. It is the result of defective fusion of the anterior chest wall. Depending on the location of the heart, ectopia cordis can be thoracic, thoracoabdominal, abdominal, and cervical.Digitalis: A genus of toxic herbaceous Eurasian plants of the Plantaginaceae which yield cardiotonic DIGITALIS GLYCOSIDES. The most useful species are Digitalis lanata and D. purpurea.Access to Information: Individual's rights to obtain and use information collected or generated by others.Borago: A plant genus of the family BORAGINACEAE.Journal Impact Factor: A quantitative measure of the frequency on average with which articles in a journal have been cited in a given period of time.Periodicals as Topic: A publication issued at stated, more or less regular, intervals.Heart Defects, Congenital: Developmental abnormalities involving structures of the heart. These defects are present at birth but may be discovered later in life.Peer Review, Research: The evaluation by experts of the quality and pertinence of research or research proposals of other experts in the same field. Peer review is used by editors in deciding which submissions warrant publication, by granting agencies to determine which proposals should be funded, and by academic institutions in tenure decisions.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.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.Tachycardia, Ectopic Junctional: A rare form of supraventricular tachycardia caused by automatic, not reentrant, conduction initiated from sites at the atrioventricular junction, but not the ATRIOVENTRICULAR NODE. It usually occurs during myocardial infarction, after heart surgery, or in digitalis intoxication with a HEART RATE ranging from 140 to 250 beats per minute.Bundle of His: Small band of specialized CARDIAC MUSCLE fibers that originates in the ATRIOVENTRICULAR NODE and extends into the membranous part of the interventricular septum. The bundle of His, consisting of the left and the right bundle branches, conducts the electrical impulses to the HEART VENTRICLES in generation of MYOCARDIAL CONTRACTION.