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Encyclopedia > Bradyarrhythmias

Bradycardia, as applied in adult medicine, is defined as a heart rate of under 60 beats per minute, though it is seldom symptomatic until the rate drops below 50 beat/min [1] (http://www.emedicine.com/emerg/topic534.htm). It is also less commonly known as brachycardia. Trained athletes tend to have slow resting heart rates, and resting bradycardia in athletes should not be considered abnormal if the individual has no symptoms associated it. The heart rate is the number of contractions of the heart in one minute. ... An athlete is a person possessing above average physical skills (strength, agility, and endurance) and thus seen suitable for physical activities, in particular, contests. ...


The term relative bradycardia is used to explain a heart rate that, while not technically below 60 beats per minute, is considered too slow for the individual's current medical condition.


This cardiac arrhythmia can be underlied by several causes, which are best divided into cardiac and non-cardiac causes. Non-cardiac causes are usually secondary, and can involve drug use or abuse; metabolic or endocrine issues, especially in the thyroid; an electrolyte imbalance; neurologic factors; autonomic reflexes; situational factors such as prolonged bed rest; and autoimmunity. Cardiac causes include acute or chronic ischemic heart disease, vascular heart disease, valvular heart disease, or degenerative primary electrical disease. Ultimately, the causes act by three mechanisms: depressed automaticity of the heart, conduction block, or escape pacemakers and rhythms. A cardiac arrhythmia, also called cardiac dysrhythmia, is a disturbance in the regular rhythm of the heartbeat. ... Many drugs are provided in tablet form. ... This article is actively undergoing a major edit. ... Santorio Santorio (1561-1636) in his steelyard balance, from Ars de statica medecina, first published 1614 Metabolism (from μεταβολισμος(metavallo), the Greek word for change), in the most general sense, is the ingestion and breakdown of complex compounds, coupled with the liberation of energy, and the consequent generation of waste... The endocrine system is a control system of ductless endocrine glands that secrete chemical messengers called hormones that circulate within the body via the bloodstream to affect distant organs. ... An electrolyte is a substance which dissociates free ions when dissolved (or molten), to produce an electrically conductive medium. ... Autoimmune diseases arise from an overactive immune response of the body against substances and tissues normally present in the body. ... Coronary heart disease (CHD), also called coronary artery disease (CAD) and atherosclerotic heart disease, is the end result of the accumulation of atheromatous plaques within the walls of the arteries that supply the myocardium (the muscle of the heart). ... There are different forms of heart disease: Coronary heart disease Ischaemic heart disease Hemorrhagic heart disease Cardiovascular disease This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...


Causes

There are generally two types of problems that result in bradycardias: disorders of the sinus node, and disorders of the atrioventricular node (AV node). The sinoatrial node (abbreviated SA node, also called the sinus node) is the impulse generating (pacemaker) tissue located in the right atrium of the heart. ... The atrioventricular node (abbreviated AV node) is the tissue between the atria and the ventricles of the heart, which conducts the normal electrical impulse from the atria to the ventricles. ...


With sinus node dysfunction (sometimes called sick sinus syndrome), there may be disordered automaticity or impaired conduction of the impulse from the sinus node into the surrounding atrial tissue (an "exit block"). It is difficult and sometimes impossible to assign a mechanism to any particular bradycardia, but the underlying mechanism is not clinically relevant to treatment, which is the same in both cases of sick sinus syndrome: a permanent pacemaker. Sick sinus syndrome, also called Bradycardia-tachycardia syndrome is a group of abnormal heartbeats (arrhythmias) presumably caused by a malfunction of the sinus node, the hearts natural pacemaker. ... Automaticity is the the ability to do things without occupying the mind with the low level details required. ... A pacemaker (sometimes called a pacer) is a competitor who enters an athletics race with little or no intention of winning, but purely to set a fast pace for other competitors to follow. ...


Atrioventricular conduction disturbances (aka an AV block) may result from impaired conduction in the AV node, or anywhere below it, such as in the His bundle.


Patients with bradycardia have likely acquired it, as opposed to having it congenitally. Also, bradycardia is more common in older patients, since both cardiac and non-cardiac causes are more likely in the elderly. A congenital disorder is a medical condition or defect that is present at or before birth (for example, congenital heart disease). ... Old age consists of ages nearing the average lifespan of human beings, and thus the end of the human life cycle. ...


Management

There are two main reasons for treating any cardiac arrhythmias. With bradycardia, the first is to address the associated symptoms, such as fatigue, limitations on how much an individual can physical exert, fainting (syncope), dizziness or lightheadedness, or other vague and non-specific symptoms. The other reason to treat bradycardia is if the person's ultimate outcome (prognosis) will be changed or impacted by the bradycardia. Treatment in this vein depends on whether any symptoms are present, and what the underlying cause is. Primary or idiopathic bradycardia is treated symptomatically if it is significant, and the underlying cause is treated if the bradycardia is secondary. A cardiac arrhythmia, also called cardiac dysrhythmia, is a disturbance in the regular rhythm of the heartbeat. ... Fatigue is a feeling of excessive tiredness or lethargy, with a desire to rest, perhaps to sleep. ... Fainting or syncope is a sudden (and generally momentary) loss of consciousness due to a lack of sufficient blood and oxygen reaching the brain. ... Dizziness (Latin: Vertigo) is the sensation of instability. ... Idiopathic is a medical adjective that indicates that a recognized cause has not yet been established. ...


  Results from FactBites:
 
Meadow Hills Veterinary Center (418 words)
Many will also present as either faster (tachyarrhythmia) or slower (bradyarrhythmia) than the normal heart rate.
Both tachyarrhythmias and bradyarrhythmias may be associated with pathophysiologic processes that cause hypoxia, or low blood-oxygen concentration.
Signs of clinically significant arrhythmias may include varying degrees of weakness, fatigue, and exercise intolerance, depending on the severity of the condition.
  More results at FactBites »

 
 

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