Bradycardia

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Related to bradyarrhythmia: bradycardia, brachycardia, sick sinus syndrome

arrhythmia

arrhythmia (ārĭᵺˈmēə), disturbance in the rate or rhythm of the heartbeat. Various arrhythmias can be symptoms of serious heart 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 pacemakers.

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 gland 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 fever) in young people or hypertensive heart disease (see hypertension) and arteriosclerotic heart diseases (see arteriosclerosis) 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 (stroke) or other organs. Atrial fibrillation is often treated with digitalis 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 defibrillators that sense dangerous fibrillations and administer an electric shock to the heart to restore normal rhythm.

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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Bradycardia

 

decrease in frequency of heart contractions to less than 60 beats per minute.

Bradycardia may be found as a normal, constitutionally conditioned phenomenon in perfectly healthy persons, in well-trained athletes, and as one of the symptoms in many diseases. More often, bradycardia is observed as a result of organic disturbances of auriculoventricular conductivity—heart blockage, myocardial infarction, and inflammatory (infectious or toxic) diseases of the heart muscle. Complete blockage of the heart with a pulse frequency of 30–40 beats per minute or less threatens brain complications: loss of consciousness, convulsions, and cessation of heart activity. Prophylaxis and treatment are directed toward removal of the cause.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

bradycardia

[¦brād·i¦kärd·ē·ə]
(medicine)
Slow heart rate.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Post ablation the EKG objectified sinus bradyarrhythmia 45 / min, QRS axis at -45 degrees and a junctional extrasystole (Figure 3).
to alleviate side effects of Neostigmine and bradyarrhythmia. Heart rate and Sp[O.sub.2] level were monitored continuously.
Pilote, "Amiodarone and the risk of bradyarrhythmia requiring permanent pacemaker in elderly patients with atrial fibrillation and prior myocardial infarction," Journal of the American College of Cardiology, vol.
The effects of CPAP therapy have been also studied in patients with OSA and bradyarrhythmia. Cornerstone series by Guilleminault et al.
On the tenth post-operative day, she became suddenly unresponsive due to a bradyarrhythmia that progressed to asystole.
Severe Obstructive Sleep Apnea with Symptomatic Daytime Bradyarrhythmia. Journal of Clinical Sleep Medicine.
More serious medical conditions, such as bradyarrhythmia and hypertension, have also been diagnosed in snorers.
Thus, although AV node reentry is typically thought of as causing tachyarrhythmias, in this circumstance, because of resetting of the sinus node and lack of ventricular contraction with the echo beat, it can present as bradyarrhythmia.
Until the late 1960s, a diagnosis of bradycardia, alternatively known as bradyarrhythmia, was tantamount to a death warrant for any dog affected by the condition, which stems from a defect in the heart's ability to allow the proper generation or conduction of electrical signals to regulate heartbeat.
Lactic acidosis and bradyarrhythmia in a child sedated with propofol.