SignSymptom infobox
Name = Bradycardia
ICD10 = ICD10|R|00|1|r|00
ICD9 = ICD9|427.81, ICD9|659.7, ICD9|785.9, ICD9|779.81

Bradycardia, as applied to adult medicine, is defined as a resting heart rate of under 60 beats per minute, though it is seldom symptomatic until the rate drops below 50 beat/min. [ Sinus Bradycardia] eMedicine] 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 with it.

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 underlain 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; 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.


There are generally two types of problems that result in bradycardias: disorders of the sinoatrial node (SA node), and disorders of the atrioventricular node (AV node).

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.

Atrioventricular conduction disturbances (aka: AV block; 1o AV block, 2o type I AV block, 2o type II AV block, 3o AV block) may result from impaired conduction in the AV node, or anywhere below it, such as in the bundle of HIS.

Patients with bradycardia have likely acquired it, as opposed to having it congenitally.Bradycardia is more common in older patients.


There are 2 main reasons for treating any cardiac arrhythmias.With bradycardia, the first is to address the associated symptoms, such as fatigue, limitations on how much a person can physically 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 depends on whether any symptoms are present, and what the underlying cause is.


Drug treatment is not needed if the pt is asymptomatic.

In symptomatic pts, draw a chem 12 and abg's to assess electrolytes and blood gases. IV atropine may provide temporary improvement in symptomatic pts.

for symptomatic pts: Atropine 0.5-1 mg IV or ET q3-5min [maximum dose is 3 mg total] (0.04 mg/kg)

ee also

* Reflex bradycardia
* Tachycardia
* Hypotension


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Look at other dictionaries:

  • bradycardia — [brad΄i kär′dē ə] n. [< BRADY + Gr kardia,HEART] abnormally slow heartbeat: below 60 beats per minute for an adult …   English World dictionary

  • bradycardia — bradycardic, adj. /brad i kahr dee euh/, n. Med. a slow heartbeat rate, usually less than 60 beats per minute. [1885 90; BRADY + CARDIA] * * * ▪ pathology       type of arrhythmia (abnormal heart rhythm) characterized by slowing of the heart rate …   Universalium

  • Bradycardia — A slow heart rate, usually defined as less than 60 beats per minute. The word bradycardia is logically derived from two Greek roots: bradys, slow + cardia, heart = slow heart. * * * Slowness of the heartbeat, usually defined (by convention) as a… …   Medical dictionary

  • bradycardia — n. slowing of the heart rate to less than 50 beats per minute. Sinus bradycardia is often found in healthy individuals, especially athletes, but it is also seen in some patients with reduced thyroid activity, jaundice, hypothermia, or vasovagal… …   The new mediacal dictionary

  • bradycardia —    A distinctly slow heartbeat, which may be a normal idiosyncrasy or with causes ranging from regular strenuous exercise to abnormally slow heart stimulus to the side effects of medication. Bradycardia is usually defined as a pulse below sixty… …   Herbal-medical glossary

  • bradycardia — noun Etymology: New Latin Date: circa 1890 relatively slow heart action compare tachycardia …   New Collegiate Dictionary

  • bradycardia — Condition in which the heart beats unusually slowly. Opposite of tachycardia …   Dictionary of molecular biology

  • bradycardia — noun The condition of having a slow heartbeat, defined as under 60 beats per minute for an adult. Syn: brachycardia …   Wiktionary

  • bradycardia — n. unusually slow heartbeat …   English contemporary dictionary

  • bradycardia — [ˌbradɪ kα:dɪə] noun Medicine abnormally slow heart action. Origin C19: from Gk bradus slow + kardia heart …   English new terms dictionary

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