Also found in: Dictionary, Thesaurus, Medical, Acronyms, Wikipedia.
Related to Bradycardia: tachycardia


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.

The Columbia Electronic Encyclopedia™ Copyright © 2022, Columbia University Press. Licensed from Columbia University Press. All rights reserved.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



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.


Slow heart rate.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Octreotide-induced bradycardia. Pharmacotherapy 1998; 18: 413-6.
Sikander et al8 also found no effect of level of block on bradycardia and need of rescue ephedrine.
Moreover, there were no bradycardia events leading to rehospitalization.
She was seen in the cardiology outpatient clinic two months prior to admission for asymptomatic bradycardia. She was not on any negative chronotropic medication.
Although there have been cases of sinus arrest in association with influenza, some requiring pacemaker placement, the patient's presentation with multiple episodes of syncope with severe bradycardia and sinus arrest requiring permanent pacemaker placement, in association with influenza B, is very unusual and possibly unique.
Bradycardia is defined as a HR <60 bpm; however, symptoms may not occur until the HR is <50 bpm.
Pacemakers are the most common way to treat Bradycardia (slow heart rhythm) to help restore the heart's normal rhythm and relieve symptoms by sending electrical impulses to the heart to increase the heart rate.
The ECGs were read as abnormal in 69 cases (43%); the most common abnormality was left ventricular hypertrophy (16 patients), followed by right ventricular hypertrophy (8), sinus bradycardia (6), and sinus tachycardia (5).
Side effects like hypotension if systolic blood pressure (SBP<90 mmHg), hypertension if mean arterial pressure (MAP>130 mmHg), tachycardia if HR>100 bpm, bradycardia if HR<60 bpm and level 4 sedation were observed and treated in both groups.