arrhythmia

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Related to arrhythmic: arhythmic, dysrhythmic

arrhythmia

(ārĭth`mēə), disturbance in the rate or rhythm of the heartbeat. Various arrhythmias can be symptoms of serious heartheart,
muscular organ that pumps blood to all parts of the body. The rhythmic beating of the heart is a ceaseless activity, lasting from before birth to the end of life. Anatomy and Function

The human heart is a pear-shaped structure about the size of a fist.
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 disorders; however, they are usually of no medical significance except in the presence of additional symptoms. The heart's rhythm is controlled by an electrical impulse that is generated from a clump of tissue on the right atrium called the sinoatrial node, often referred to as the heart's natural pacemaker. It travels to a second clump of tissue called the atrioventricular node and then to the ventricles.

Bradycardia, or slow heartbeat, is often present in athletes. It may, however, indicate conduction problems, especially in older people. In one type of bradycardia, called sinoatrial or atrioventricular block, or heart block, rhythm can be maintained by implanted electrodes that act as artificial pacemakerspacemaker, artificial,
device used to stimulate a rhythmic heartbeat by means of electrical impulses. Implanted in the body when the heart's own electrical conduction system (natural pacemaker) does not function normally, the battery-powered device emits impulses that trigger
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.

Tachycardia, or heartbeat faster than 100 beats per minute in the adult, can be precipitated by drugs, caffeine, anemia, shock, and emotional upset. It may also be a sign of overactivity of the thyroid glandthyroid gland,
endocrine gland, situated in the neck, that secretes hormones necessary for growth and proper metabolism. It consists of two lobes connected by a narrow segment called the isthmus. The lobes lie on either side of the trachea, the isthmus in front of it.
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 or underlying disease. Flutters, and the even faster fibrillations, are rapid, uncoordinated contractions of the atrial or ventricular muscles that usually accompany heart disorders. Atrial fibrillation may be idiopathic, the result of rheumatic mitral valve disease (see rheumatic feverrheumatic fever
, systemic inflammatory disease, extremely variable in its manifestation, severity, duration, and aftereffects. It is frequently followed by serious heart disease, especially when there are repeated attacks. Rheumatic fever usually affects children.
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) in young people or hypertensive heart disease (see hypertensionhypertension
or high blood pressure,
elevated blood pressure resulting from an increase in the amount of blood pumped by the heart or from increased resistance to the flow of blood through the small arterial blood vessels (arterioles).
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) and arteriosclerotic heart diseases (see arteriosclerosisarteriosclerosis
, general term for a condition characterized by thickening, hardening, and loss of elasticity of the walls of the blood vessels. These changes are frequently accompanied by accumulations inside the vessel walls of lipids, e.g.
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) in older people. It may result in a rapid pulse rate and may be associated with thrombus formation in the atria and a risk of embolization to the brain (strokestroke,
destruction of brain tissue as a result of intracerebral hemorrhage or infarction caused by thrombosis (clotting) or embolus (obstruction in a blood vessel caused by clotted blood or other foreign matter circulating in the bloodstream); formerly called apoplexy.
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) or other organs. Atrial fibrillation is often treated with digitalisdigitalis
, any of several chemically similar drugs used primarily to increase the force and rate of heart contractions, especially in damaged heart muscle. The effects of the drug were known as early as 1500 B.C.
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 and other drugs that regulate heart rhythm or heart rate. It may also be treated by catheter ablation, in which an electrode produces heat to destroy cells causing the arrhythmia. Ventricular fibrillation is a sign of the terminal stage of heart failure and is usually fatal unless defibrillation is achieved by immediate direct-current defibrillation. Some tachycardias can be managed by the implantation in the upper chest of small defibrillatorsdefibrillator,
device that delivers an electrical shock to the heart in order to stop certain forms of rapid heart rhythm disturbances (arrhythmias). The shock changes a fibrillation to an organized rhythm or changes a very rapid and ineffective cardiac rhythm to a slower, more
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 that sense dangerous fibrillations and administer an electric shock to the heart to restore normal rhythm.

Arrhythmia

 

disruption of the normal rhythm of the heart. Arrhythmia is manifested as an increase in frequency (tachycardia) or a slowing (bradycardia) of the heart contractions, in the appearance of premature or additional contractions (extrasystole), in heart palpitations (paroxysmal tachycardia), and in complete irregularity of the intervals between individual contractions (fibrillation). Arrhythmia may appear, among other causes, as a result of heart disease (myocarditis, cardiosclerosis); it may be functional or be caused by disturbance of the nervous regulation of the heart—for example, when the interconnection between the auricles and ventricles is interrupted (heart block). So-called respiratory or juvenile arrhythmia (acceleration of heartbeat upon inspiration) is a physiological phenomenon in children and adolescents. Some arrhythmias cause disturbance of blood circulation, unpleasant feelings of “irregularity of heart action,” dizziness, and the like. Other arrhythmias are not felt by patients. Treatment is directed toward removing the basic disease and restoring the normal heart rhythm.

arrhythmia

[ā′rith·mē·ə]
(medicine)
Absence of rhythm, especially of heart beat or respiration. Also spelled arhythmia.
References in periodicals archive ?
Conclusion: Wavelet decomposition-based template matching technique achieved satisfactory delineation of normal and arrhythmic electrocardiogram dynamics.
Because it affects children too, the term Sudden Arrhythmic Death Syndrome is now more commonly used.
However, if the source of interest has a period that varies from period to period (for instance, arrhythmic ECG), then joint diagonalization of the autocorrelation matrices at time lags corresponding to integer multiples of the fundamental period leads to erroneous results.
The frequency and rate of either premature ventricular complexes (PVC) or nonsustained ventricular tachycardia (NSVT) episodes as well as any transient conduction disturbance in a given patient with high risk features for SCD may well be established with the aid of Holter ECG and risk for future cardiac arrhythmic events can be predicted with reasonable probability.
Patients who underwent catheter ablation had a significant reduction in the risk of arrhythmic events.
At the 2-year follow-up in DEFINITE, there were 11 arrhythmic deaths in the medically managed control group and 3 in the ICD arm, for a highly significant 74% relative risk reduction favoring device therapy.
In a dramatic display of flexibility, several hundred older bees stopped foraging, lost their circadian rhythms, and pitched in to assume arrhythmic infant care, Bloch and Robinson report in the April 24 NATURE.
Results Show MTWA to Be a Strong, Independent Risk Factor for Major Arrhythmic Events
Pathologist Dr Esther Youd told the inquest there was no logical explanation for Dr Cambridge's death apart from sudden cardiac arrhythmic death syndrome which could have been inherited.
The Oliver King Foundation was set up by the family of 12-year-old Oliver King, who died from Sudden Arrhythmic Death Syndrome (SADS) in 2011, moments after winning a swimming race at King David High School, in Childwall.

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